Israeli Prime Minister Benjamin Netanyahu arrived in Britain on Wednesday for talks with Prime Minister David Cameron as hundreds of pro-Palestinian and pro-Israeli demonstrators clashed outside Downing Street.
Police intervened to break up the scuffles as around 500 protesters gathered outside Cameron's residence in London ahead of a meeting of the two leaders on Thursday.
The Israeli leader's focus was firmly on Iran as he touched down, once again criticising a landmark nuclear deal between Tehran and Western powers agreed in July.
Iran's supreme leader Ayatollah Ali Khamenei said Wednesday that he would not permit negotiations with the United States beyond those which culminated with the deal.
"Khamenei is not giving supporters of the agreement any room for illusion," said Netanyahu in response to Khamenei's comments, adding that Iran wanted to "destroy the state of Israel".
"All responsible countries must cooperate in order to stop Iran's terrorism and aggression which, to my regret, will only increase as a result of the agreement," Netanyahu said.
Meanwhile at Downing Street, police officers separated the two groups of protesters into pens and took away at least two demonstrators following scuffles and chanting by both sides, according to an AFP photographer.
"At around midday a number of demonstrators made their way out of both pens and onto Whitehall, briefly blocking the road," police said in a statement.
"A small number of protesters were arrested for a variety of offences including obstruction, assault and criminal damage to a motor vehicle," it added.
Around 400 pro-Palestinian activists protested against Netanyahu's visit, some chanting "arrest Netanyahu" and "war criminal". Others waved flags, including at least two from Lebanon's Shia movement, Hezbollah.
Facing them were around 100 pro-Israeli demonstrators, many waving the Israeli flag.
More than 108,000 people have signed a petition urging the arrest of Netanyahu for war crimes, enough for the issue to be considered for debate in Britain's parliament.
Israel's embassy in London called it a "meaningless publicity stunt".
In 2014, Israel launched an offensive against Gaza Strip which left 2,251 Palestinians dead and 73 on the Israeli side, most of them soldiers.
Britain is pushing for a two-state solution to resolve the Israeli-Palestinian conflict and "will reinforce this message to Mr Netanyahu during his visit," according to an official response to the petition.