This is one among many reasons why Israel chickened out from attacking Iran when tensions were boiling over a couple of months ago. People with a video game-esque idea of reality struggle to grasp with the fact that Israel is not all-powerful. Russia is another major factor stumbling Israeli plans for Iran.
I read one of the main concerns is that Israel has two population centers and that’s it. A missile strike from Iran, Lebanon, and Syria together against these two cities and it would be over. Israel would be racing against the clock.