I don't see why Israel would want regime change in Iran. The current one may hate them, but it's keeping the country poor and weak. Previous regime was starting to be a threat.
Who do you think the previous regime was? The Shah was installed by the US and was friendly to Israel. Under the Islamic Republic, Iran has been hostile to Israel and funded proxy organizations that have been in conflict with it.
Shah Pahlavi was installed by the US but soured with us later on. OPEC involvement was a big part of that. By the end of his reign, he was openly calling the US a puppet of Israel and criticizing both countries' actions there, and the US considered Iran a free agent.
I think an honest assessment of the history reveals that the Islamic Republic has been far more hostile to Israel and far stabler than the Shah, who oversaw a deeply unpopular monarchy and was deposed by his own people
I don't disagree with this, it's just that there's no reason to assume Israel simply wants the least hostile Iranian government. We never saw a real effort to replace the Islamic Republic, not even now. Likewise there was never an attempt to replace Hamas in the Palestinian territories.
Well also, about Pahlavi being deposed by his own people, who really knows.
What do you think Israel’s objective is then? It seems rather clear to me that they have expansionist ambitions which necessitate defeating their neighboring foes, who are backed by Iran. A non-hostile Iran is an Iran that does not back these foes. There has been no attempt to replace Hamas because Israel’s goal is the ethnic cleansing of Gaza.
They want to expand into the Palestinian territories and also want to not be existentially threatened, both of which require weakening their enemies. They aren't going to get a friendly Iran no matter what, but they can get a weak one.
They also need to maintain Western support. That's billions in both military aid and payoffs to neutral countries like Egypt and Saudi Arabia, plus diplomatic ties. Netanyahu's administration wants to maintain support from its own people too. Having enemies isn't a completely bad thing for those reasons.