Cuba’s government is elected by the people. Their elections are objectively more democratic than what the US has. If every member of the current government stepped down and new elections were held, more or less the same people would be elected. The Cuban people proudly support socialism and anti-imperialism, and any fair election will reflect that (which is why Cuba has the government it has).
But I suspect Rubio et al already know that. When he says he wants “regime change”, what he means is he wants the current elected, democratic government to step down and in it’s place, Rubio will act as viceroy and for the country to operate as an undemocratic colony of the US.
I think last time around, the US was signaling - directly or indirectly - that they were “just” targeting nuclear sites and so long as Iran didn’t “overreact”, then the US would just leave it at that.
The attack that the US/Israel seem to be preparing for appears to be much more substantial and brutal. Closing the Strait is a huge deal, but Iran needs to be willing to use it.
I’m assuming a significant part of the reason for the unprovoked attack on Venezuela and forcing them into a neo-colonial relationship - forcing them to route their oil through the US system - was to try and prevent an oil price shock to Americans in the event of a major attack on Iran and the closure of the Strait.