Palestine is/was a not-quite-nation-state kept mostly under Israel's thumb for decades. October 6 was a wild moment but it was probably the hardest hit Hamas could muster after years of prep. Iran is one of the prime centers of power in the middle east, a nation state with enough economic and political power to have a nuclear program, and who was mostly staying out of things regarding the Palestinians. Regardless of the ethical considerations, I can't see how opening this second front with a much more powerful enemy could be a good idea for Israel.