A video clip, posted on social media, showed Gideon Falter being told by police he was "quite openly Jewish" and causing a "breach of peace".
The chief executive of the Campaign Against Antisemitism (CAA) was wearing a kippah skull cap when he was stopped from crossing a road near the demonstration in the Aldwych area of London last Saturday.
An officer told him: "You are quite openly Jewish. This is a pro-Palestinian march. I am not accusing you of anything, but I am worried about the reaction to your presence."
Another officer said: "There's a unit of people here now.
"You will be escorted out of this area so you can go about your business, go where you want freely or if you choose to remain here because you are causing a breach of peace with all these other people, you will be arrested."
The clip showed the officer saying Mr Falter's presence was "antagonising".
After the incident, Mr Falter was critical of the Met and said there were "no-go zones for Jews".
He said: "Despite being told repeatedly that London is safe for Jews when these marches are taking place, my interactions with police officers last Saturday show that the Met believes that being openly Jewish will antagonise the anti-Israel marchers and that Jews need protection, which the police cannot guarantee."
He added: "Instead of addressing that threat of antisemitic violence, the Met's policy instead seems to be that law-abiding Jewish Londoners should not be in the parts of London where these marches are taking place.
"In other words, that they are no-go zones for Jews."
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Mr Falter said he will be walking in London on 27 April, adding that no part of the capital should be unsafe.
The CAA said in a statement that Mr Falter had gone to a synagogue last Saturday and then went for a walkabout with some other people.
It added: "They were openly Jewish but had no badges or placards, weren't shouting anything, did not say or do anything political and did not seek to engage with any protesters or join any counter-protest. They sought to walk through London, wherever we wanted, as Jews. But they were not able to."
Tens of thousands of pro-Palestinian protesters gathered in London last Saturday to call for a ceasefire in the Israel-Hamas war in Gaza and urge the UK government to stop all arms sales to Israel.
In a statement, the Met said they were aware of the video and "fully acknowledge the worry it has caused, not only to those featured, but also anyone who watches it".
The force said: "We recognise the conflict between Israel and Hamas continues to be an issue of concern for many Londoners, and this includes the regular protests and marches in central London.
"Everyone has the right to travel throughout the capital in safety."

The storm first hit Oman at the weekend, killing at least 21 people, before pounding the United Arab Emirates (UAE) on Tuesday with its heaviest rains since records began in 1949.
Two Filipina women died after suffocating inside a vehicle during the floods in the UAE, a statement by the Philippines' Department of Migrant Workers said.
Meanwhile, a Filipino man was killed after his vehicle fell into a sinkhole in the country, the department added.
An Emirati man in his 70s also died when his vehicle was swept away by floods in the northern Ras Al Khaimah emirate.
The exact number of deaths caused by the storm in the UAE is not yet known as officials there have not released any information.
The UAE, a federation of seven emirates that consists of Abu Dhabi, Dubai, Sharjah, Ajman, Umm Al Quwain, Ras Al Khaimah and Fujairah, has an arid desert climate and typically has little rainfall.
However, this week's massive storm blew through all seven of the country's sheikhdoms this week - with more than 5.59 inches of rain falling on Dubai on Tuesday.
The city has a typical yearly average of 4.7 inches of rain.
Lightning and flash floods
Lightning flashed across the sky, and it sometimes touched the tip of the world's tallest building - the Burj Khalifa.
Many roads and other areas in Dubai have insufficient drainage due to the lack of regular rainfall, causing flooding.
The main road connecting Dubai, the most populous emirate, with Abu Dhabi remained partially closed on Friday, while an alternative route saw vehicles driving through low water on the hard shoulder past abandoned cars and buses.
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In the UAE's north, including in the emirate of Sharjah, local media reported people were still trapped in homes on Friday.
Meanwhile, long-haul carrier Emirates said on the X social platform that it would again halt local check-in for passengers traveling on its flights until early Saturday to "support operations recovery from the recent bad weather at our Dubai hub".
As of Friday morning 1,478 flights to and from Dubai had been cancelled since Tuesday - approximately 30% of all flights, according to aircraft flight tracking website FlightRadar24.
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The tarmac at Dubai International Airport, the world's busiest for international travel, had been flooded on Tuesday as planes made their way around what looked more like a lake.
Early reports linked the extreme weather to "cloud seeding", in which small planes flown by the government go through clouds burning special salt flares, which can increase precipitation.
However, experts later said the practice could not have caused so much rain and the weather was more likely to do with factors including climate change.

Outlining his plans to reform the welfare system if the Conservatives win the next general election, Rishi Sunak said "unemployment support should be a safety net, never a choice" as he promised to "make sure that hard work is always rewarded".
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Mr Sunak said his government would be "more ambitious about helping people back to work and more honest about the risk of over-medicalising the everyday challenges and worries of life" by introducing a raft of measures in the next parliament. They include:
• Removing benefits after 12 months for those deemed fit for work but who do not comply with conditions set by their work coach - such as accepting a job offer
• Tightening the work capability assessment so those with less severe conditions will be expected to seek employment
• A review of the fit note system to focus on what someone can do, to be carried out by independent assessors rather than GPs
• Changes to the rules so someone working less than half of a full-time week will have to look for more work
• A consultation on PIP to look at eligibility changes and targeted support - such as offering talking therapies instead of cash payments
• The introduction of a new fraud bill to treat benefit fraud like tax fraud, with new powers to make seizures and arrests.
He insisted the changes were not about making the benefits system "less generous", adding: "I'm not prepared to balance the books on the backs of the most vulnerable.
"Instead, the critical questions are about eligibility, about who should be entitled to support and what kind of supports best matches their needs."
But Labour said it was the Tories' handling of the NHS that had left people "locked out" of work, and a disabled charity called the measures "dangerous".
The latest data from the Office for National Statistics (ONS) shows 9.4 million people aged between 16 and 64 were "economically inactive", with over 2.8 million citing long-term sickness as the reason.
Mr Sunak said 850,000 of them had been signed off since the COVID pandemic and half of those on long-term sickness said they had depression, with the biggest growth area being young people.
He also claimed the total being spent on benefits for people of working age with a disability or health condition had increased by almost two-thirds since the pandemic to £69bn - more than the entire budget for schools or policing.
"I will never dismiss or downplay the illnesses people have," said the prime minister. "Anyone who has suffered mental ill health or had family and friends who have know these conditions are real and they matter.
"But just as it would be wrong to dismiss this growing trend, so it would be wrong to merely sit back and accept it because it's too hard, too controversial, or for fear of causing offence."
The prime minister said he knew critics would accuse him of "lacking compassion", but he insisted "the exact opposite is true", adding: "There is nothing compassionate about leaving a generation of young people to sit in the dark before a flickering screen, watching as their dreams slip further from reach every passing day.
"And there is nothing fair about expecting taxpayers to support those who could work but choose not to.
"It doesn't have to be like this. We can change. We must change."
But Labour said the "root cause of economic activity" was down to the Tories' failure on the health service, with record NHS waiting lists hitting people's ability to get back in the workplace.
Acting shadow work and pensions secretary Alison McGovern said: "After 14 years of Tory misery, Rishi Sunak has set out his failed government's appalling record for Britain: a record number of people locked out of work due to long-term sickness and an unsustainable spiralling benefits bill.
"Rather than a proper plan to get Britain working, all we heard today were sweeping questions and reheated proposals without any concrete answers."
Liberal Democrat leader Sir Ed Davey called it "a desperate speech from a prime minister mired in sleaze and scandal", adding: "Rishi Sunak is attempting to blame the British people for his own government's failures on the economy and the NHS and it simply won't wash."
Meanwhile, disability charity Scope said the measures were a "full-on assault on disabled people", adding they were "dangerous and risk leaving disabled people destitute".
James Taylor, director of strategy at the charity, said calls were already "pouring in" to their helpline with people concerned about the impact on them, adding: "Sanctions and ending claims will only heap more misery on people at the sharp end of our cost of living crisis."

Labour Party chair Anneliese Dodds wrote to Lancashire Police asking for an inquiry after The Times reported he had made a late-night phone call to an aide asking for funds to pay off "bad people".
Mr Menzies told the paper he contests the allegations against him.
In a statement, Lancashire Police said: "We can confirm that we have now received a letter detailing concerns around this matter and we are in the process of reviewing the available information in more detail."
Mr Menzies lost the Conservative Party whip in Westminster following the reports on Wednesday evening, while the party investigates the claims.
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In a drill over Edwards Air Force Base, the pair of F-16 fighter jets flew at speeds of up to 1,200mph and got as close as 600 metres during aerial combat, also known as dogfighting.
One was manned, while the other jet was a modified version of the F-16, called the X-62A, or VISTA (variable in-flight simulator test aircraft).
While in flight, the AI algorithm relies on analysing historical data to make decisions for present and future situations, according to the Defence Advanced Research Projects Agency (DARPA), which carried out the test.
This process is called "machine learning", and has for years been tested in simulators on the ground, said DARPA, a research and development agency of the US Department of Defense.
In 2020, so-called "AI agents" defeated human pilots in simulations in all five of their match-ups - but the technology needed to be run for real in the air.
Pilots were on board the X-62A in case of emergency, but they didn't need to revert controls at any point during the test dogfight, which took place in September last year and was announced this week.
The result represents a "transformational moment in aerospace history", DARPA said in a statement.
It did not reveal which aircraft won the dogfight.
"The potential for autonomous air-to-air combat has been imaginable for decades, but the reality has remained a distant dream up until now, said Secretary of the Air Force Frank Kendall.
"In 2023, the X-62A broke one of the most significant barriers in combat aviation. This is a transformational moment, all made possible by breakthrough accomplishments of the X-62A ACE team."
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Colonel James Valpiani, a commandant at the US Air Force test pilot school. said: "Dogfighting is a perfect case for the application - machine learning.
"Dogfighting is extremely dangerous. So, if machine learning can operate effectively in an environment as dangerous as air-to-air combat, it has great potential to earn the trust of humans as we look to applications that are less dangerous but equally complex."
He added: "The X-62A is an incredible platform, not just for research and advancing the state of tests, but also for preparing the next generation of test leaders.
"When ensuring the capability in front of them is safe, efficient, effective and responsible, industry can look to the results of what the X-62A ACE team has done as a paradigm shift.
"We've fundamentally changed the conversation by showing this can be executed safely and responsibly."