The group wore badges and carried flags identifying them as coming from Force FF.
Several of the men wore balaclavas while others had masks to protect themselves from COVID-19.
Mr Farage, the leader of the Brexit Party, condemned their presence at the protest on Twitter.
He tweeted: “Terrifying scenes in Brixton today.
“A paramilitary-type force marching in the streets.
“This is what the BLM movement wanted from the start and it will divide our society like never before.”
READ MORE: Brexit activist targeted by Black Lives Matter protesters in London
“Hope is what people need right now and they are leading the way to get there.”
The three arrests concerned suspicion of a fight, suspicion of racist assault and suspicion of assault against an emergency worker.
Police accompanied the demonstration which they said was to end at 8 p.m.
Assistant Deputy Commissioner Laurence Taylor, who managed the event, said: “Today’s gatherings have been largely peaceful and we thank our communities for working with us to ensure that the voices of the community can be heard safely and responsibly in order to keep everything safe. “
Metropolitan Police added, “Officers were on hand throughout the day to work with community organizers and speak to those in attendance to ensure a successful day free of anti-social behavior and violence, resulting in only three arrests.
“Conditions had been imposed on the demonstrations. These included for participants to assemble in three specific areas of Brixton and for the protests to end at 8:00 p.m.
“These conditions were cleared following reports that some participants intended to block the A23 – the main road through Brixton.
“It would have caused significant disruption to these local residents and the surrounding areas.”
Protests against racial justice exploded across America and beyond after the death of George Floyd at the hands of a police officer in the US city of Minneapolis.
Derek Chauvin, the former officer involved, has been charged with second and third degree murder.
In Britain, major protests were held in June to support and oppose the removal of statues of some important historical figures.