So far three arrests have been made as thousands of people swamped Trafalgar Square, Oxford Circus and Piccadilly Circus.
A statement from the Met Police read: “Officers have made three arrests at Piccadilly Circus.
“One person was arrested after they were seen displaying a placard that could incite hated, contrary to Section 12 of the Terrorism Act.
“Two other people were arrested; one for breaching conditions of Section 12 of the Public Order Act and the other for assaulting a police officer.
“All three have been taken to central London police stations.”
The police said that the demonstration was being “closely monitored” as it made its way through the capital.
Similar protests are also taking place in Manchester, Bristol, Liverpool and Newcastle, among other cities and towns.
People at the rally could be heard chanting “Gaza, stop the massacre” and “from the river to the sea, Palestine will be free”.
Last night, five people were arrested at a pro-Palestinian protest at King’s Cross station in London.
Transport Secretary Mark Harper said he had given an order to allow police to stop the demonstration on Friday evening.
A section 14 notice had been made at the station which meant police could end the protest on the grounds it was disruptive to passengers.
The force, working with the Metropolitan Police, also escorted a group of about 50 protesters away from the area to Euston.
