1. Iran would never lay a finger on Israel due to Israel's Arrow interception system, let alone America.
2. There is a major difference between weapon's grade uranium for a nuclear warhead capable of any worry and the use of nuclear technology for development uses...
3. America has nukes, as do several other countries...Iran is trying to catch up, and if you don't have a nuclear warhead, you really don't have anything to back you up. This is based off the assumption that Iran's intentions are at all related to a WMD.

No worries.