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.
Well also, about Pahlavi being deposed by his own people, who really knows.
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.