This article from ABC News has Barack Obama saying that, if sanctions don't work, he believes Israel is going to strike Iran. The way he phrased this, it sounds like it was told to him "on background" by Israeli officials.
This article from Reuters has an Israeli Cabinet Minister saying the sanctions against Iran are failing to stop nuclear weapon development, making an Israeli attack "unavoidable."
Two things are going on here: first, Israel is trying to jawbone or bluff Iran into accepting the European "deal" to accepts the carrots of aid and avoid the sticks of sanctions without having to attack. Second, if the jawboning doesn't work, Israel is getting the world ready for the attack that is to come.
Of course Iran knows part one, and doesn't want to give in. What is unclear is whether Iran believes part two as they should. Israel has a real track record of destroying nuclear facilities in their neighborhood.
Do you remember the doomsday device mentioned at the end of the film Dr. Strangelove? What if Iran has a nuke set to go off if the Israelis attack? Would the world believe it was Iranian or believe the Israelis used one or more of their nukes on Iran? If the latter, would the world eradicate Israel?
Perhaps what would actually happen is less critical than what the Iranian leadership, always more emotional than logical, believes would happen. We live in interesting times....