Dozens of police officers were gathered outside King’s Cross station where the protest was planned to begin around lunchtime on Saturday.
Footage appeared on social media of officers appearing to arrest a man who is heard screaming as he kneels on the pavement.
A Met Police spokesman said the rally, organised by the Save Our Rights group, was not exempt from the “prohibition on gatherings” under regulations brought in to combat the spread of coronavirus.
Chief Superintendent Stuart Bell, policing commander for this weekend, said: “The Met has a proud history of facilitating protest. However, our city is in a critical fight against Covid-19 and we cannot allow gatherings to jeopardise the progress and sacrifices our communities have made in fighting this virus.
“That is why we will be taking action in relation to prohibited gatherings on the streets of London, including those related to protest across the capital this weekend.
“Our top priority is public safety and that is why we cannot allow individuals to break the law and put their health and the health of their friends, family and the wider community at risk. If you are planning on attending a gathering, I would urge you to reconsider and stay at home.”