Footage showed the group, which appeared to be largely made up of men, gathered at the Kent port on Saturday.
They were later shown marching through the town and chanting "whose streets? our streets!" and "stop the boats" as dozens of police officers followed.
The protests - which have been condemned by the government - brought traffic on roads to the UK's busiest international ferry and passenger port to a halt, delaying some ferry services.
Kent Police said no arrests were made during the "spontaneous protest".
In a post on X the force said: "Kent Police responded to a spontaneous protest in #Dover during the morning of Saturday 5 September.
"No arrests were made. Traffic is flowing normally, and all involved had dispersed by midday."
Behaviour of protesters condemned
Politicians have roundly condemned the actions of protesters, with a government spokesperson saying: "The right to peaceful protest is fundamental to our democracy, but we condemn the behaviour in Dover and the travel disruption it has caused."
They added: "We thank policing partners and travel providers who we continue to work with to ensure the safety of passengers and the wider community."
Chris Vinson, leader of the Conservative group on Dover District Council, said the demonstration appeared to be a "co-ordinated" group of "several hundred masked men".
He said it had "brought the town to a standstill" and left "stacks of people" stuck in their cars or workplaces.
He added: "I'm not aware that there's been any violence, although clearly, having the path of your vehicle blocked by men wearing black paramilitary gear and balaclavas is extremely intimidating, especially when it's not clear why they're there, and the police weren't aware and so haven't been able to warn people in advance and make sure that they are made to feel safe.
"I know people who have worked night shifts in the port who are being prevented from leaving for fears for their safety. Women who are in cars feeling intimidated, people stuck in traffic - who obviously are without toilet facilities - queues way back on the A20 and the other approach roads into Dover."
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Asked about the protest on Sky News' Sunday Morning with… Jon Sopel, Business Secretary Jonathan Reynolds said: "Well, I condemn it. I mean, peaceful protest [is a] central part of British life.
"But that's not dressing up in costumes like this and disrupting people's lives. So I would condemn it, but I condemn the disruption it caused for local people as well.
"But it was resolved. It was resolved. But clearly that's not something we would want or expect to see on the streets of Britain."
His comments echoed those made by Mike Tapp, the Labour MP for Dover and Deal, in an article for the Sunday Mirror.
"Dover knows better than most the pressures immigration and border disruption can bring," he wrote.
"We have lived on the front line of the small boats crisis for years. We have also endured queues and gridlock caused by changes to cross-Channel travel. So the last thing Dover needs is another group deliberately blocking our roads."
Addressing the policing, he added: "I will be asking why, whether intelligence was missed, and whether additional officers - including mutual aid from forces such as the Met - can be mobilised quickly enough when Dover is targeted again."
Robert Jenrick, Reform UK's Treasury spokesperson, told Sky News: "I've always hated people obstructing other people doing their daily life, whether it's Just Stop Oil or whatever. And I don't like people going around in balaclavas, which is obviously very intimidating.
"But do I understand why people are extremely frustrated? Yes, absolutely."
Who was responsible for the demonstration?
An associate of right-wing activist Tommy Robinson appeared to claim credit for the protests.
Sharing a video of demonstrators on Instagram, Daniel Thomas, known as Danny Tommo, wrote: "It's time! Protect our country! And more importantly our women and children! This is our warning!"
Campaign group Hope Not Hate linked the action to the Patriot Platform, a group Tommo recently launched.
He described the Patriot Platform as "the resistance standing against the downfall of the United Kingdom", with contingents across the country.
A coordinated plan
Robinson, whose real name is Stephen Yaxley-Lennon, also posted about the protests on social media, suggesting they were part of a coordinated plan.
In a post on X he wrote: "Simultaneously at different locations across Dover patriots have mobilised to close down the port."
Tommo and Robinson have regularly appeared together at political rallies and events, with some media outlets and Hope Not Hate describing Tommo as Robinson's "right-hand man".
Hope Not Hate said the protests showed a growing trend of "anti-migrant vigilantism coming to a head in the public eye".
It added: "Today, we could see Patriot Platform for what it is: a far-right network of men happy to intimidate and inconvenience an entire town for what was effectively a publicity stunt."
Sabby Dhalu, of Stand Up To Racism, said: "It's hard to believe that any other protest group from Just Stop Oil to the Palestine movement would have been allowed to blockade a major port without mass arrests and prison sentences."
The Prince of Wales will be joined by his aunt, the Princess Royal, who is attending next week in a private and personal capacity as godmother of the new king, Haakon VIII.
It follows the death of the much-loved monarch, who died on 28 August at the age of 89.
The funeral will take place on Wednesday at Oslo Cathedral, with mourners including his widow Queen Sonja.
In keeping with the precedent that the sovereign does not attend funerals of other heads of state, the duty falls to William.
Last April, William represented his father at the funeral of Pope Francis in the Vatican.
Charles paid a tribute to his "dear cousin" and "much-loved kinsman and friend" after the news of Harald's death was announced.
He praised Harald's "unwavering dedication" and his "kindness, compassion and deep sense of duty echoed from across the sea and across the decades".
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The late Queen Elizabeth II and King Harald were second cousins and shared the same great-grandparents, King Edward VII and Queen Alexandra.
Harald, who was known for his humour and informal style, has been hailed as an inclusive "people's king" who modernised the Norwegian monarchy during his 35-year reign.
William and the now-Princess of Wales carried out an official tour to Norway in 2018, dining with King Harald and Queen Sonja at the Royal Palace, where Harald described them as "family" and praised their support of the late Queen.
The Norwegian sovereign entered the banquet arm-in-arm with pregnant Kate, who was expecting Prince Louis at the time and wearing an Alexander McQueen gown. The king's wife and William walked behind them.
William and Kate also visited the ski slopes with the then-Crown Prince Haakon and Crown Princess Mette-Marit, now the new King and Queen.
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The Irish great became a three-time undisputed world champion by dominating the previously unbeaten Frenchwoman over 10 rounds at Croke Park in Dublin.
Two judges scored the fight 100-90 and the other 98-91.
Her victory saw the 40-year-old add the vacant WBC title to her WBO, WBA and IBF belts.
The match at the Gaelic games stadium, which Taylor calls the "Cathedral of Irish sport", drew 83,000 fans.
"Croke Park! We did it," Taylor said as she saluted the crowd after a final onslaught that saw Pili pushed to the ropes in a flurry of punches.
"Every one of you here helped me win. You were with me in London 2012, you got me through the heartbreak of Rio [2016, where she lost in the quarter-finals], you stayed with me when I turned pro, you travelled around the world to watch me - Boston, Brooklyn, Manhattan - now you're here with me."
The 2012 Olympic gold medallist walked to the ring for the last time to All Hail King Jesus by Bethel Music and Bethany Wohrle.
A barrage of fireworks marked the end of her era in Irish sport.
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After the interviews and emotional tributes and family embraces, Taylor walked around the ring before placing her gloves in the centre according to tradition.
"I don't know of any other country that would sell 80,000 tickets [for women's boxing]. Ireland is the only country," she had said earlier.
"She was a very awkward opponent and a great opponent. Thank you very much to her for being involved in this epic night."
Footage shows the twin-seat Phantom F4 jet going up in flames after crashing during a low-altitude manoeuvre at Tanagra air force base, around 40 miles north of the Greek capital, on Saturday.
The bodies of the two pilots were recovered during a rescue operation.
Helicopters, planes and 85 firefighters attended the scene - some distance from the viewing area at Athens flying week. An evacuation order was issued and organisers cancelled remaining events planned over the weekend.
Thousands of people were in attendance, but no injuries were reported among the spectators.
Prime Minister Kyriakos Mitsotakis said: "The sense of grief is widespread, and our thoughts are with the families of the two pilots we lost.
"It is a reminder of the daily danger faced by Greece's aviators, who remain on constant standby to protect Greece's skies."
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Cyprus' defense minister Vasilis Palmas posted on X: "It is with deep sadness that I learned of the death of the two officers of the Hellenic air force, who lost their lives in the tragic accident that occurred during the air show at Tanagra air base."
The air force has declared three days of mourning in the wake of the crash.