“It’s a movement against austerity laws — that’s what it’s about,” she added, noting right-wingers had been “opportunistic” in adopting it.
A separate demonstration by dozens of Brexit supporters wearing yellow vests also took place in central London on Saturday.
At the outset, police arrested one of the organisers on suspicion of a public order offence.
It reportedly related to a controversial incident outside parliament on Monday, when a group harangued pro-EU figures, including chanting “Nazi” at prominent Remain supporting MP Anna Soubry during live TV interviews.
Ahead of Saturday’s protests Nick Lowles, CEO of the anti-racism group “Hope Not Hate” accused Britain’s far-right of “attempting to copy the French ‘yellow vests’ protests in order to stir up trouble and harass, threaten and attack their political opponents.”