We should probably shut off Iran's spigot entirely. Their economy almost certainly would collapse, and then -maybe- there would be enough support for an insurrection to accomplish the stated goal of regime change.

I don't think we're willing to do that. You'd spike oil prices vastly higher than they are now, and likely set off a world-wide recession. The damage to global agriculture and chip making (fertilizer and helium) would be pretty terrible, and the economies of several other Gulf nations (Iraq, Kuwait, Bahrain, Oman, UAE) would also collapse as Iran responded by sealing off Hormuz. Saudi can adapt somewhat, unless the Iranians can call in the Houthis to go after Red Sea traffic. Things wouldn't be so hot in receiver countries either, like Japan and Taiwan. And Europe definitely doesn't want the refugee problem that would create.

And even then, it might not work. The regime is fresh off slaughtering folks who weren't even engaged in insurrection, and they probably have sufficient asymmetrical control over the use of force in the countr to keep any uprising in check for quite a while. Crater the Iranian economy and you create an even greater risk of "rally 'round the flag." Authoritarian regimes use external enemies as part of their propaganda, and you just make it that much easier when even opponents of the regime know that you're taking action to tank the country.