The crowd outside New Scotland Yard, close to the Houses of Parliament, were seen hugging each other as others held signs reading: "My body, my choice."
Another at the protest in central London on Saturday afternoon held a sign saying: "No more lockdown."
Around 20 people appeared to be in the crowd, which included young children.
Police told the protesters to go home before arresting a man who did not comply.
Gatherings of any sort are banned under the UK's rules to slow the spread of coronavirus which were rolled out on March 23.
The Metropolitan Police said in a statement: "A small number of protesters gathered near New Scotland Yard earlier today.
Officers engaged with the protesters, encouraged them to go home and the group subsequently dispersed. One man arrested."
The UK has been on coronavirus lockdown for around six weeks, after Boris Johnson ordered Brits to stay at home except for essential work, food shopping, exercise and medical trips.
The Prime Minister may announce an end to the lockdown for some businesses, like factories, shops and office-based companies, on May 26, the Sun has reported.
But this plan is only the "best hope", and could change if the current slowdown in coronavirus cases picks back up again.
Business Secretary Alok Sharma will set out detailed instructions next week on how businesses in different sectors should end the lockdown.
Despite the protest, the majority of Brits are worried about lockdown being lifted after more than a month of being told to stay home to save lives, a survey revealed.
The study, by Ipsos Mori, found that more than 60 per cent of Brits would be uncomfortable doing regular activities like going to bars or restaurants.
The London gathering came after hundreds of people protested against US lockdown rules in California and Michigan despite a rising death rate.
People packed out the streets in the city south of Los Angeles, defying an order to close all of Orange County's beaches which was issued after "concerning" images emerged of large crowds of beachgoers.
Speaking to the Los Angeles Times, one protester, Andrew Norman, said: "I served in the Army and fought tyrants and dictators overseas and this has gone too far.
"I didn’t do that to come back here and live under a tyrant in my own country."
California's hospitalisation appears to be improving, according to Governor Gavin Newsom.
But he condemned the protests, saying: "We can screw all that up. We can set all that back by making bad decisions," he said. "All of that works because people have done an incredible job in their physical distancing."