Only time will tell how this war will be seen legally, but imo at this moment Israel is not in violation of international law. It explicitly allows strikes with civilian casualties if the casualties are "proportional" to the military advantage gained, which in the case of Hamas leaders using civilians as human shields seem to be the case, as ugly as it is. It depends on whether Israel is lying or mistaken about their targets, but none of us can know that at this moment. But since dead civilians are much more useful for Hamas' interests than for Israel's interest, I think it's pretty safe to say that Israel is at least making an effort to be precise and likely just doesn't care about other casualties.