KNOW WHEN TO FOLD 'EM. One idea I've seen kicking around the past couple of days is that talk of military strikes against Iran may be part of some kind of clever gamesmanship designed to achieve a diplomatic resolution. I think people need to think harder about that. Airstrikes would, at best, delay Iranian acquisition of nukes. Giving in to the United States would, of course, entail abandoning the quest for them entirely. So the structure of Bush's offer, under this theory, would be "either give up your nukes or else I'll slightly delay the point at which you can get them." That, I think, isn't quite in "offer they can't refuse" territory. Indeed, they'd have no reason whatsoever to accept that offer. It's a pointless threat.
The only way to make this work would be to put carrots on the table. "Give up your nukes and we'll lift our sanctions and grant you diplomatic recognition, or else I'll use force to slightly delay the point at which you can go nuclear." This will work, of course, only if Iran would prefer diplomatic and trade relations with the US to having a nuclear bomb. But if that is their preference, then the threat of airstrikes adds nothing to the equation -- you could just put the straight-up nukes for sanctions trade on the table and you'd get the same result one way or another. Airstrikes would be pointless in any case, and precisely because they're pointless there's no point in threatening to use them.
Now, conservatives will say we shouldn't offer carrots because Teheran can't be trusted. Bush thinks it's wrong to offer concessions to "evil" regimes (it's appeasement, see) and that's why he won't put any on the table. If that's your mindset, there are only two options -- let the evildoers go nuclear (see North Korea) or launch a disastrous war (see Iraq). It'd be nice to find a middle ground, but there's really nothing there.