Tens of thousands of Israelis gathered in Tel Aviv on Saturday to mourn peace-seeking prime minister Yitzhak Rabin on the 18th anniversary of his assassination by a Jewish extremist.

The demonstrators were mainly young people representing a wide political spectrum but protesting against Israeli radicals opposed to peace with the Palestinians, an AFP reporter said.

The demonstrators carried portraits of Rabin -- who was assassinated after addressing a rally in the same square on November 4, 1995 -- and banners with slogans against racism and intolerance.

"Stop the price tag, defend democracy," read one banner, referring to so-called "price tag" attacks on Palestinians by Jewish extremists opposed to the dismantling of settlements in the occupied West Bank.

"My grandfather was assassinated for peace, and you owe this peace to us, to all of us," Rabin's grandson Yonatan Ben-Artzi said in a speech to the crowd, addressing Prime Minister Benjamin Netanyahu.

Media said 30,000 people joined the rally in Tel Aviv's Rabin Square, where the premier was gunned down by Jewish extremist Yigal Amir, who is currently serving a life sentence.

Amir had hoped to derail the 1993 Oslo accords signed by Rabin and the Palestinians, a landmark agreement aimed at resolving the decades-old conflict.

Organisers of Saturday's rally had planned it to roughly coincide with the anniversary of the assassination in the Jewish Calendar, which falls next week.

An official ceremony will be held on Tuesday at the Jerusalem cemetery where Rabin is buried.