UK Prime Minister Boris Johnson has labelled an ugly incident in a London neighbourhood linked to the current Israel-Palestine crisis as "shameful racism".
A disturbing video showed a group of men in cars shouting abuse at passers-by in a suburb with many Jewish residents.
The anti-Semitic abuse comes during the worst violence for years in Israel and Palestine.
The dispute began in Jerusalem as Jewish settlers attempted to take land from Arab residents, many of who had lived in homes there for decades.
Hamas, a group that controls the Gaza Strip south of Tel Aviv, then launched rockets towards Israel. Israeli defence forces responded with a huge number of missiles flattening homes and in some cases entire tower bocks.
At least 192 people, including 58 children, have been killed in Gaza in the past week, with more than 1200 wounded in the escalating conflict. At least 13 Palestinians have been killed in the occupied West Bank, close to Jerusalem.
Israel's death toll stands at 10, including two children.
Last weekend, protests were held in major cities across the world in support of Palestine, including London.
On Sunday, a video was posted on social media which appeared to show a convoy of vehicles travelling through north London laden with Palestinian flags.
A man can be seen using a megaphone to hurl anti-Semitic abuse out of one of the car's windows at locals in St John's Wood, 5km from central London.
Among other things, he can be heard using violent sexual language.
According to the Jewish News, the convoy was later also seen around Brent Cross, 11 km from the city's CBD.
Talking to the BBC, the person who filmed the video said they did "not feel safe" following the incident.
"I cried. How is this the world we live in today?" the resident, who did not want to be identified, said.
"I felt immediately frightened and appalled that this is happening in this country. What if I was walking alone wearing something that identified me as Jewish? What might have happened?
"I don't feel safe in my own home, and that's what terrifies me."
London's Metropolitan Police said it had arrested several people in connection with the incident.
"Four men were arrested on suspicion of racially aggravated public order offences," said the Met.
"They were taken into custody at a west London police station where they remain."
Prime Minister Boris Johnson tweeted that there was no place for anti-Semitism in the UK.
"Ahead of Shavuot (a Jewish religious festival), I stand with Britain's Jews who should not have to endure the type of shameful racism we have seen today."
Opposition leader Sir Kier Starmer said the incident was "utterly disgusting".
"Anti-Semitism, misogyny and hate have no place on our streets or in our society. There must be consequences," he tweeted.
There is no place for antisemitism in our society. Ahead of Shavuot, I stand with Britain’s Jews who should not have to endure the type of shameful racism we have seen today.
"Hate crimes are inexcusable and have no place in our city. I've been in touch with the Met Police Commissioner about the appalling reports of anti-Semitic attacks this weekend."
The Palestine Solidarity Campaign, which helped organise the London protest, condemned the incident which it labelled "vile anti-Semitism".
Also at the weekend, there were reports a rabbi was assaulted in Essex, east of London.
Sky News UK has reported that two teenagers confronted the man in the suburb of Chigwell and damaged his car. The assistant rabbi was then attacked with an object and was hospitalised.
Essex Police are investigating the incident.
The UN Security Council met on Sunday amid global alarm at the escalating violence.
UN Secretary-General Antonio Guterres pleaded for an immediate end to the "utterly appalling" violence and warned of an "uncontainable security and humanitarian crisis".
But the council meeting, already delayed by Israel's ally the United States resulted in little action.
"The fighting risks dragging Israelis and Palestinians into a spiral of violence with devastating consequences for both communities and for the entire region," Guterres said.
"It has the potential to unleash an uncontainable security and humanitarian crisis and to further foster extremism, not only in the occupied Palestinian territory and Israel, but in the region as a whole."