I do not agree that Israel supported regime change in Syria.
My impression is that both the Israeli Right and Left were comfortable with a prolonged Cold War with Bashar Assad.
Obviously, Assad's logistical support of Hezbollah in southern Lebanon is a stressful military issue and a clear danger to the Israeli public.
On the other hand, it's also my impression that the Israeli Right and Left recognize that Assad lives in a very dangerous neighborhood, and without a Syria-Iran alliance, Assad would have a very short life.
Bottom Line - the price of Iran's friendship with Assad is that Assad must continue to support Hezbollah.
Bang for the buck: WHAT should we do?
Yes, I think they were, and the IDF also. But the Israeli govt took up a very adventurist policy in regard to Syria - of regime change, and support for the very group, Al Nusra, which is now being targetted by Turkey.