Some 1,000 people participated in the first significant demonstration of its type Saturday night in Tel Aviv, The Jerusalem Post said.
"Israelis Against The War" posted details of the demonstration on a Facebook page calling to oppose a military strike on Iran, which said: "We will not agree to an irresponsible Israeli attack on Iran, leading to a war with an unknown end-date and casualty count."
The demonstration was inspired by a campaign launched by an Israeli couple last week who posted Facebook photos and a message to Iranians opposing military action.
Last Monday, Ronny Edri, 41, and his partner, Michal Tamir, 35, uploaded pictures of themselves on Facebook with the caption: "Iranians, we will never bomb your country. We love you."
Defense Minister Ehud Barak said last week while he supports the recent round of sanctions imposed on Iran, all options would remain on the table.
In interviews on Israel Radio and Army Radio Thursday, Barak said the United States has more time to consider a strike on Iranian nuclear sites because of its military superiority while Israel feels directly threatened. He said intelligence agencies from both countries were working together on the issue.
"Israel cannot afford to wait but negotiations and sanctions can buy a few more months," Barak told Army Radio.