just as Iran had no choice to respond to the bombing of the embassy/consulate/annex building.
Iran declared war on Israel more than 40 years ago. They threaten to obliterate Israel off the map on a practically daily basis. They don't just speak though, they have created, supported, funded, controlled, and cheered many different countries and terrorist organizations over the years who are actively trying to do just that. Iran is directly responsible for thousands of Israeli lives, and untold billions upon billions of dollars of military defense, and the unquantifiable damage of a civilization living under constant threat of rocket attacks with only seconds to make it to a shelter.
Israel has assassinated many of its military and nuclear program leaders over the years. The notion that this attack was some sort of escalation that *needed* to be responded to is silly.
One thing that Iran has not done is send cruise and ballistic missiles themselves. I'm not sure if you saw the size of those things, they are massively powerful, *each* with the ability to kill hundreds. The fact that Israel and its allies were mostly able to defend them doesn't take away from how close they were to massive catastrophes. If this is not responded to, it becomes the new normal, just like rocket attacks in southern Israel (and now north). Speak to people who live there, it is not a way of life that any government should allow their citizens to live under. And it's to Israel's great shame that they have allowed their citizens to live like that for years.
So yes, Israel has no choice but to respond. Not because they said they would, but because their survival depends on it.