Here is the core of the conflict.
Iran wants to spread its tentacles throughout the muslim world. Not because it seeks to destroy. Instead, it wants a shia leadership in the muslim world. This terrifies Israel; they feel far less threatened by sunni's. Iran has already succeeded in Lebanon via Hezbollah -- again terrifying Israel -- and that is why Iran is supporting Asad in Syria. And, Russia and China both support Iran, from an arms perspective and oil perspective -- again, that sends shivers up Israel's spine. They wouldn't stand a chance if they attacked Israel. And it would cripple the US economy because the US would then have to make a choice - Israel, or, preserve its relationship with Russia and China, the latter which has been buying up a lot the US debt (along with wealthy gulf businessmen).