No collateral damage is acceptable, but it is unrealistic to think that there will be no collateral damage in war. It is also unrealistic to think that Israel would not respond to the October 7 massacre, and unacceptable for Hamas to use the Palestinian people as human shields to avoid retaliation.
What does that boil down to? Israel has every right to strike back at Hamas. Hamas also has every right to fight against Israel. Because of the way Hamas has dug in to the civilian population and infrastructure, civilian casualties are a given. The number of civilian casualties is a function of two things:
How intensively Israel tries to kill Hamas and degrade their capabilities, and,
How effectively Hamas uses the Palestinian population as human shields.
In other words, both Israel and Hamas are to blame for civilian casualties. This is the same in every war. Civilians in a war zone always get fucked, no matter who started the war.