A man has been arrested on suspicion of inciting racial hatred after Saturday's pro-Palestine march in London.
He is now in custody, the Metropolitan Police said.
The man "filmed shouting racist abuse in Whitehall" the force said in a post on X, formerly Twitter.
About 100,000 demonstrators gathered in the capital in a show of solidarity for Palestine and to demand an immediate end to Israel's bombardment of Gaza.
Immigration minister Robert Jenrick told Sunday Morning With Trevor Phillips on Sky News that the chanting of jihad on the streets during the protests was "completely reprehensible".
The government wanted to make sure the police did "everything that they can to protect British Jews", he added.
While the protest was largely peaceful, Scotland Yard said on Saturday evening 10 arrests had been made for firework-related offences, a public order offence, affray, assaulting an emergency worker and public order offences.
It added that five police officers had "received minor injuries".
The Met said has seen a huge rise in antisemitic and Islamophobic hate crimes from the start of October.
Another person was arrested at an Israeli vigil hosted by the Jewish Leadership Council in Trafalgar Square on Sunday afternoon.
The Met said officers made an arrest for a racially aggravated public order offence and the suspect was in custody.
The war has sparked protests across the Arab world and beyond, with crowds gathering in Lebanon, Iraq, Jordan, Turkey and Egypt, as well as in Ireland, Indonesia, Malaysia and South Africa.
Hundreds of people marched in Rome on Saturday, with some demonstrators holding signs saying "Palestine, Rome is with you" and "No peace until we get freedom".
In Australia, thousands gathered in central Sydney, shouting "shame, shame, Israel" and "Palestine will never die".
And in New York, hundreds of protesters marched to US Senator Kristen Gillibrand's Manhattan office, many shouting "ceasefire now".