I'm wondering if you'd apply the same standard on the flip side? Per Hamas, they are engaged in a war with Israel, so by your standard they are justified in their rocket attacks killing Israeli civilians who have nothing to do with the war?
There are a LOT of videos from Gaza when Israel notified civilians to leave a building before it destroys it. That seems contrary to the goal of killing civilians.
The other obvious thing is - since Israel is already totally smeared as a genocider (eg this story) it could be argued that it can do whatever it wants and suffer no further PR damage. So to the extent that it still shows restraint - it's either because they don't want to kill civilians or because they are still playing to an audience with a discerning moral compass internationally.