A photo of Patrick Hutchinson carrying the man over his back at the weekend was widely shared on social media, with many calling him a hero.
It followed violent clashes between police and far-right protesters claiming to be defending statues in central London.
Hutchinson and his friends spotted an altercation involving the lone white man and young black demonstrators on the steps near Royal Festival Hall in London on Saturday.
He said the man was on the floor and that he and his four friends moved in to stop him from being trampled.
He told the BBC: “I scooped him up into a fireman's carry and marched him out with the guys around me, protecting me and shielding me and protecting this guy from getting any further punishment.
"I wasn't thinking, I was just thinking of a human being on the floor. It wasn't going to end well had we not intervened.
"We did what we had to do. We stopped somebody from being killed."
Hutchinson carried the injured man over his shoulder while the others formed a barrier around them, before handing him to nearby police officers.
The white man did not utter a word and the group have not spoken to or seen him since.
Hutchinson, a personal trainer and grandfather, had formed a group with four of his friends with the aim of protecting young Black Lives Matter protesters from getting caught up in violence.
He said: "At the moment the scales are unfairly balanced and I just want things to be fair, for my children and my grandchildren."
A total of 113 people were arrested in London on Saturday following violent clashes between far-right protesters and police.
Twenty-three police officers were injured as several hundred demonstrators, mostly white men, took over areas near the Palace of Westminster and Trafalgar Square and hurled missiles, smoke grenades, glass bottles and flares at police officers.
Thousands of Black Lives Matter protesters have taken to the streets of the UK in the past two weeks following the death of African-American man George Floyd at the hands of US police officers.
Another member of Hutchinson’s group, Pierre Noah, 47, a bodyguard and martial arts teacher from Croydon, spoke about rescuing the white man.
"They were going to beat him up and stamp on him,” he said. "If we didn't do that I wouldn't like to think what would have happened to the poor guy.
"We wanted to save his life and save the Black Lives Matter campaign as well. We were ready to help anyone, no matter what their colour, it's for the right purpose.”
Saturday’s far-right protest was condemned by Boris Johnson as "racist thuggery" and described as "mindless hooliganism" by police.
A 28-year-old was charged with outraging public decency after a photo appeared to show a man urinating on a memorial to PC Keith Palmer, who was stabbed to death in the 2017 Westminster terror attack.