Sarkozy was speaking after a summit of G8 and other leaders in Italy at which they agreed on the need to pursue a negotiated deal with Tehran to halt a programme which Western powers fear hides a plan to acquire nuclear weapons.
"Israel should know that it is not alone and look at all this calm. If I have fought so hard in the name of France to get people talking about Iran it's also a message to the Israelis that they are not alone," he said.
Many in Israel would regard any move by Iran, whose leaders are virulently anti-Israeli, to acquire nuclear weapons as an existential threat, and its leaders have warned they may be forced to take military action.
US President Barack Obama has tried to persuade Iran to open talks on the issue to head off conflict, but Tehran has yet to respond to his opening, and Sarkozy warned that if the regime failed to do so "there will be sanctions."
Israel carried out an air strike on 1981 on an Iraqi nuclear facility when the late Saddam Hussein, its sworn enemy, was in power in Baghdad.
