I don't think you understand the capabilities difference - Israel has the nuclear option if they are threatened existentially. But lets take that off the table a moment.
Iran's capabilities are their missiles, manufacturing capabilities. Their Refineries, and strategic energy reserves are in known locations and are the lynch pin of Iran's economy. And finally, the Nuclear R&D facilities are in known places. All of those are the targets - and Israel absolutely has the capacity to take it out- just not the strong justification.
If Iran continues striking Israel, Israel is going to feel the pressure to decapitate Iran as a threat to them.
The fall out of this is more interesting:
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China loses access to Iranian Oil for the short to mid term - it will take time to restore capabilities.
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Russia loses access to Iranian missiles - without production capabilities, and depleted stocks, Iran will not be able to sell missiles to Russia let alone drones.
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Iran's economy will be in shambles - that could very well open the door to coup or revolt.
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Iran would unload as many missiles as it possibly could - which could be devastating. But that would come down to just how many interceptor missiles Israel would have available, along with other air defence options.
If you want a "Why would trump support this" - there you have it. It reaffirms US obligation to support it's allies, It puts economic pressure on china, and denies Russia access to weapons - which should help push them to the negotiating table.
In reality, I would more expect Iran to back off. Then again - With Israel obliterating Iran proxies, Iran may feel the pressure to complete a nuclear deterrent and Israel may end up wanting to decapitate Iran as a threat BEFORE they gain that capability... what a bloody mess.