Two elderly supporters of Julian Assange were hauled away after protesting outside his bail hearing in London.
Pictures showed officers detaining the man and woman when they had gathered with others at Westminster Magistrates Court on Wednesday.
On Monday district judge Vanessa Baraitser rejected Wikileaks founder Assange’s extradition to the United States citing him a "suicide risk" but he was then denied bail after the judge said he could flee while a US appeal was pending.
Police confirmed seven people were detained for breaching coronavirus regulations outside the court.
The protesters were later reported for consideration of a fixed penalty notice and ordered to leave the area.
Police also shut down an anti-lockdown protest in Parliament Square that began at 12pm.
The Met confirmed 21 people were arrested on suspicion of breaching coronavirus regulations, among other offences.
Footage on social media showed a large police presence and a number of demonstrators being removed from the scene.
The force had warned protesters would face “enforcement action” by officers if they were to turn up to any planned events.
Deputy Assistant Commissioner Laurence Taylor said on Wednesday: “For those planning on demonstrating, you are reminded of your obligation to adhere to the government guidelines and stay at home.
“If people are found to be in breach of regulations, put in place to keep the public safe, then they can expect to see enforcement from officers.
“This will not just be organisers of the gatherings but participants too – by now everyone knows their part to play in stopping the spread of the virus.
“People that gather as part of this protest today risk the health of Londoners. I will not tolerate this and that is why we have a policing plan in place to disperse crowds and if necessary, take enforcement action.”
The Met said the public should expect officers to be more “inquisitive” about why they are “out and about” during England’s third national lockdown.
Londoners breaching COVID legislation “are increasingly likely to face fines”, the force said in a statement, adding: “Where officers identify people without a lawful reason to be away from home they can expect officers to move more quickly to enforcement.”
Although officers will still apply the “4 Es” approach – engaging, explaining, encouraging and then enforcing – Scotland Yard said it had issued “refreshed instructions” to hand out fines “more quickly to anyone committing obvious, wilful and serious breaches” like those attending or organising parties or other large illegal gatherings.
People not wearing masks when they should be “and without good reason” can also expected to be “fined – not reasoned with”, the force warned.
Watch: What you can and can't do during England's third national lockdown