Protesters from the Youth Demand campaign group were moved on by police during a pro-Palestinian rally in central London.
The campaigners began gathering at Lincoln’s Inn Fields, Holborn, on Saturday morning and made their way to King’s Cross station.
Some held banners which read “stop arming Israel” while others let off green-coloured flares before being moved along by police.
Youth Demand said its supporters divided into two groups and at around 12.15pm a group of 40 blocked traffic on Euston Road near King’s Cross.
The Metropolitan Police issued the protesters with a warning under section seven of the Public Order Act, Youth Demand said, and the group moved on after 10 minutes.
No arrests were made, Scotland Yard said.
The action is part of Youth Demand’s plans for demonstrations every Tuesday and Saturday in April.
Last Thursday, six people from Youth Demand were arrested at a meeting, the Metropolitan Police said.
A Met spokesperson previously said: “Youth Demand have stated an intention to ‘shut down’ London over the month of April using tactics including ‘swarming’ and road blocks.
“While we absolutely recognise the importance of the right to protest, we have a responsibility to intervene to prevent activity that crosses the line from protest into serious disruption and other criminality.
“On Thursday March 27, officers raided a Youth Demand planning meeting where those in attendance were plotting their April action.
“Six people were arrested on suspicion of conspiracy to cause a public nuisance.”
