They'd be cutting their own throats if they did. No oil going out means no money coming in. No money means no food. How long would the already distressed Iranian people put up with that state of affairs? Not too long, I'd say.

This assumes we are dealing with rational people and not religious zealots. The majority of the Iranian people are rational but there leadership may not be. the Iran hostage crisis was not exactly rational and could have resulted in a far worse outcome. No mater where you stand politically on the issue it is just not a good idea to go around poking much bigger people in the eye. Eventually you will get their attention.

As well with the economy as bad as it is there is nothing like a war to distract people.