Are you sure that stopping it will actually minimize the number of deaths in the long run? Is it better to kill 20000 people in a short time to reach permanent peace, or to save some of those people and then repeat the whole ordeal each 2 years, with more and more bloodshed?
I don’t pretend to have an answer, but war brings up very hard to answer moral questions.
Things are not simple, and a simplistic take of this matter is very prevalent, sadly. I mean, what are even the real numbers? Did you forget about the Hamas rocket hitting a hospital in Gaza, which they claimed was Israel's bombing that killed 500 civilians? Later they settled on 50, when it was widely accepted that it was their doing.
Fighting Hamas is hard, mostly because it uses civilian population and infrastructure to its benefit, but what are the alternatives? reward Hamas' actions by letting them off the hook? I haven't heard any other suggestion on how do deal with Hamas except for fighting them head on.
It would be great to "defeat Hamas" as a solution, but I'm not sure how that's feasible at this point without razing Gaza.