Some 82 counter-protesters have been arrested during the pro-Palestine march in central London "to prevent a breach of the peace", the police said.
The Metropolitan Police added: "They’re part of a large group of counter-protesters we have been monitoring who have tried to reach the main protest march.
"We will continue to take action to avoid the disorder that would likely take place if that happened.”
Counter-protesters were seen clashing with officers before the demonstration began.
Scuffles broke out as police attempted to stop a crowd of people carrying St George’s flags marching along Embankment towards Whitehall, where the Cenotaph is located, shortly after 10am on Saturday.
The group, which had been chanting “England ’til I die” pushed through the police barrier, with some shouting “let’s have them” as officers hit out with batons
Further clashes with police took place in Chinatown with counter-protesters chanting: “You’re not English any more” towards officers.
Police managed to disperse the crowd, splitting them into two smaller groups which were seen running in the direction of Piccadilly Circus.
One man was arrested on suspicion of possession of a knife and another for possession of a baton.
Two more arrests included one for assaulting a police officer and a second for possession of a controlled substance.
A “large” group of about 100 counter-protesters was earlier detained near to Westminster Bridge - held under police powers to prevent a disturbance.
Meanwhile, thousands of people began marching from Park Lane near Hyde Park shortly before 1pm as part of what is expected to end up being one of the largest political marches in British history.
Chants of “free Palestine” and “ceasefire now” could be heard as the protesters set off.
An Armistice Day service took place at the Cenotaph on Whitehall at 11am, which passed off peacefully with a two-minute silence being observed.
The Met Police posted on X, formerly Twitter: “While the two minutes’ silence was marked respectfully and without incident on Whitehall, officers have faced aggression from counter-protesters who are in the area in significant numbers.”
Home Secretary Suella Braverman remains under pressure from all sides after accusing the police of bias when they resisted pressure to ban the pro-Palestinian march.
After her comments were widely criticised and sparked calls for Mr Sunak to sack her, Mrs Braverman on Friday expressed her “full backing” for the Metropolitan Police at a meeting with Commissioner Sir Mark Rowley.