Campaigners congregated on the steps of London's Royal Courts of Justice on Sunday, highlighting an increase in anti-semitism.
Police reported that at least 3,500 people attending the #notoantisemitism rally, although eyewitnesses put the figure at around 4,500.
Gerry Gable, a political activist and former editor of the anti-fascist magazine Searchlight addressed the crowd, saying: "Antisemitism is like a cancer, it must be stopped."
The Campaign Against Anti-Semitism (CAAS) said that Jewish people in Britain are facing "levels of anti-semitism not seen in this country for almost a century".
Protestors are demanding greater action by the police and the government to take measures against hostility towards Jewish people in the UK.
"Unless we act now to force the issue, anti-Semites will continue to go unpunished and the nature of British society will change.
'Wave of widespread anti-Semitism'
"We must unite to turn the tide," the CAAS said in an online statement.
"There is a wave of widespread anti-Semitism sweeping across Europe, and also here in Britain.
"British Jews are afraid. Citizens are looking to the police and government to enforce the law with zero-tolerance against antisemites, as they do in other cases of racism.
"It is only through zero-tolerance that the tide of antisemitism can be turned. This demand is backed by the full spectrum of Jewish organisations," Jonathan Sacerdoti, spokesman for CAAS, said.
Chief Rabbi Ephraim Mirvis addressed the crowd alongside Maajid Nawaz, a Muslim activist and co-founder of Quilliam, a counter-extremism think tank.
Douglas Murray, a conservative commentator and associate director of the Henry Jackson Society, is also expected to appear.
In a Jewish Chronicle poll, people were asked: "Since the protests against the war in Gaza began, have you or your friends had a discussion about whether there is a future for Jews in the UK?"
Around 63% said yes.
The Community Security Trust, which works to protect the Jewish community, has reported that July was the second-worst month of anti-Semitism since British records began, with 240 incidents logged.
— Marcus Dysch (@MarcusDysch) August 31, 2014