LONDON — Pro-Palestinian anti-Israel protesters blocked roads outside the British parliament in London on Saturday, demanding an immediate ceasefire in the Israel-Hamas war and clashing with police who prevented them from marching across Westminster Bridge.

Videos posted on social media showed police blocking protesters’ access to the bridge and a Reuters reporter said there had been several small scuffles. Unable to fully access the bridge, where they had planned to unfurl banners, protesters instead occupied the surrounding roads.

Police said they had imposed a legal order limiting the location of the protests and that by 3 p.m. (1500 GMT) people had begun to disperse. Those who refused to comply with an order to leave could be arrested, police said.

London, like other Western cities, has seen regular and sometimes large demonstrations calling for Israel to halt the bombardment of Gaza triggered by the shock October 7 attack by Hamas terrorists who killed more than 1,200 people in southern Israel and kidnapped some 240.

Hamas health officials say 22,722 people have so far been killed in Israel’s bombardment of Gaza. The figure cannot be verified, doesn’t differentiate between civilians and combatants, and includes Palestinians killed by errant rocket fire from within Gaza. Israel says it has killed 8,500 terrorists since the start of the war.

Saturday’s action was smaller than previous mass marches but comes two days before the British parliament returns to work after its Christmas break. The protest was designed to push politicians to adopt a harder stance toward Israel.

So far, Britain has stopped short of calling for an immediate ceasefire, with Foreign Secretary David Cameron arguing that any such agreement could be unsustainable and may worsen violence without a plan for longer-term peace.

Most previous protests in London have been coordinated with police, but police said the organizers of Saturday’s protests had refused to share details of their plans.