A fundamental principle of the Laws of Armed Conflict (LOAC) is distinguishing military and civilian targets, and minimizing harm to the latter. That applies to all sides in every war. [0]
In warfare, generally all sides are outraged, filled with hatred and revenge. They wouldn't be killing each other otherwise. That is not an exceptional situation, it's the norm; that's what the LOAC was written for. 1200 civilian deaths, though absolutely horrible, unforunately also is well within the norm for warfare. 100,000+ have died in places and times, including at US hands.
Obviously Hamas didn't follow that principle (they seem to have intentionally violated it). I can't say how well Israel is doing it, but it's an essential issue. Saying 'we're angry' or 'our people were killed' is not exceptional in warfare and does not create exceptions.
[0] https://www.justsecurity.org/89489/expert-guidance-law-of-ar...