An estimated 10,000 demonstrators set off from Portland Place at noon, moving through Regent Street, Haymarket and Piccadilly before gathering in Whitehall for speeches at about 2pm.
By this point, the crowd had doubled, the Metropolitan Police said.
People carried banners which read “end the killing” that were accompanied by harrowing images of the bloodshed since the conflicted erupted. Others declared “free the children”, “freedom to Palestine” and “Boycott Israel”.Officers disrupted the march in Haymarket, where two women were arrested - one on suspicion of setting off a smoke bomb or flare and another who is accused of chanting slogans that may incite racial hatred (a public order offence).
At another during the protest, one other person was arrested for a public order offence and another was taken into custody for obstructing police.
The force put in several conditions under which the Stop the Genocide, Ceasefire Now rally would be able to go ahead.
These included finishing up by 5.30pm and the authorisation for officers to demand the removal of face coverings throughout the borough of Westminster between 10am on Saturday to 1am on Sunday.
There was previously a row over whether the march should be allowed to finish in Whitehall - something the police eventually "yielded" to.
Organisers have accused the Metropolitan Police of being "politicised and repressive".
People were seen disrupting the protest in Haymarket.
Officers arrested a woman on suspicion of setting off a smoke bomb or flare.
A second woman was arrested under section 18 of the Public Order Act.
She is accused of chanting slogans that may incite racial hatred.
— Metropolitan Police (@metpoliceuk) February 3, 2024
Palestine Solidarity Campaign (PSC) director Ben Jamal said: "We have been involved in intense and difficult negotiations with the Met.
"The police have now yielded to allow us to march to Whitehall, from where we will send our message to the Government that it must not be complicit in Israel’s genocide in Gaza by continuing arms exports, military cooperation and diplomatic support.
"This is the eighth National March for Palestine and they have brought hundreds of thousands of people to the streets of London in orderly and peaceful demonstrations.
"Unfortunately, the policing of the marches has become increasingly politicised and repressive over several months.
"We will not allow the attempts to deter people from marching to stop us nor to distract from us delivering the central message calling for a permanent ceasefire to end the genocide, for an end to occupation and a dismantling of Israel’s system of apartheid."
Scotland Yard said the vast majority of previous demonstrators have done so in a lawful and peaceful way, but a minority have broken the law and arrests have been made for supporting Hamas militants and anti-Jewish hatred.
Mr Ward warned police will "deal swiftly" with anyone who carries placards and banners or makes statements that cross the line into religiously or racially aggravated offences.
He said: "We respect the right of people to protest, but other Londoners and visitors have rights as well.
"I understand the cumulative impact of repeated protests since October on businesses, residents and those who want to travel into the West End.
"Getting the balance between competing rights can be difficult, but we will do it independently, impartially and always within the law."
Teams monitoring the protest by CCTV will seek to identify other crimes or find suspects.
A Met spokesman said: "Our first priority is to apprehend suspects immediately, but if this is not possible due to dense crowds we will seek to identify and locate them as soon as possible.
"There will be a highly visible police presence with road closures in place for the safety of those taking part.
"Any closures will be lifted as soon as it is safe to do so to minimise disruption.
"Leaflets will be distributed setting out clear guidance to those taking part on the sort of behaviour that is likely to lead to arrest."
PSC is calling for a ceasefire, "an end to occupation and for Israel’s system of apartheid to be dismantled".
The eighth National March for Palestine comes nearly four months since Hamas launched its deadly attack on Israel on October 7 and Israel responded with a bombardment of the Gaza Strip.