Thousands of protesters carried banners and placards opposing coronavirus rules and vaccines. Police officers dispersed large crowds of demonstrators at Trafalgar Square following the march through the city.
The Metropolitan Police said at least 10 people have been arrested at the rally.
Scotland Yard added that the demonstration failed to comply with the terms of their risk assessment, Government guidelines and people were not maintaining social distancing.
The force tweeted at 5pm: “Ten arrests have so far been made by officers policing the ‘Stop the New Normal’ protest.
“This protest is no longer exempt from the regulations and we are asking demonstrators to leave.
Ade Adelekan, police gold commander for Saturday, said: “As COVID-19 cases rise across the capital, it is vitally important for us all to stick to the regulations which are there to keep everyone safe.
“Throughout London, we will have officers on hand to respond to reports of breaches but to also engage with communities on the rules.
“I would urge those looking at attending a protest tomorrow that these events may not be exempt from the regulations if the organisers do not comply with the regulations and submit a satisfactory risk assessment.
“This could result in crowds being dispersed or indeed enforcement action being taken by officers on scene.
“Everybody has a personal responsibility to stick to the regulations and help prevent the transmission of Coronavirus.
“We will not allow the health of Londoners to be put at risk and officers and we will take action against those groups or individuals who flagrantly and dangerously breach these rules.”
