Binyamin Netanyahu, Israel's prime minister, has won pledges from Francois Hollande, the French president, to keep Iran from developing nuclear weapons.
Netanyahu visited Paris on Wednesday and praised France for the pressure it has put on Iran and called for "even tougher sanctions" than the ones currently in place.
But the prime minister had no sympathy for any possible Israeli military strike against Tehran.
Netanyahu has previously warned that his government would strike Iranian nuclear facilities as sanctions have not stopped Tehran's quest for developing an atomic bomb.
Iran insists its nuclear programme is intended for generating power and is not meant for military use.
Hollande said he wanted "concrete acts and gestures" from Iran to show it was not pursuing nuclear arms, adding that he would back "other sanctions" if Tehran failed to do so.
Netenyahu said: "The sanctions are taking a bite out of Iran's economy ... unfortunately they have not stopped the Iranian [nuclear] programme."
He told reporters: "Given the history of the Jewish people, I would not sit by and write off a threat by those who say they are going to annihilate us."
Netanyahu said Arab nations would also be "relieved" if Iran were prevented from obtaining nuclear arms.
Hollande is opposed to Netanyahu's argument for a possible military action and has supported a push for tougher EU sanctions on Iran while wanting to keep the door open for dialogue.
Netanyahu and Hollande also talked about the possibility of resuming Israeli-Palestinian peace negotiations in Paris.
The Israeli premier said he was ready to hold talks at the French presidential palace: "President Hollande can invite [Palestinian Authority President Mahmoud] Abbas to the Elysee [presidential palace] ... I'm here, I'm ready."
France has long opposed Jewish settlement building in the West Bank and east Jerusalem - a major obstacle in the Israel-Palestine peace process - and supports the creation of a Palestinian state.
It also voted for Palestinian membership in UNESCO, the Paris-based United Nations cultural and educational body, a year ago.
Mahmoud Abbas, the leader of the Palestinian Authority, is now pushing ahead his plan to seek upgraded observer status at the United Nations in New York next month, despite US and Israeli threats of financial or diplomatic retaliation.
Netanyahu has criticised the Palestinian bid for international recognition as a state while efforts to revive the Israel-Palestine peace process continue.