"Regime change" is just rhetoric and unlikely to be the real policy objective. American Presidents have always wanted the same thing from Iran: to have zero Uranium enrichment (or only just enough for civilian applications), and to relinquish their current stockpile to someone else (ideally the US of course). The Trump administration has framed it as "regime change" because it's a more convenient moral narrative because it leverages Iran's barbaric authoritarianism and aligns itself with Irani public sentiment. I don't think the West has ever politcally cared if Iran became a democracy or not.