All nations are built and maintained by violence, either directly or by threat of it.
It's a core component of sovereignty. To be able to call your government sovereign you must have the capacity to resist both external and internal actors from being able to overthrow you.
You must also be willing and able to use violence against those under your rule who disobey your laws (i.e, arresting a murderer).
Anytime you are doing any kind of military or police action within a civilian area there is always the risk of unintended civilian harm.
If police and military forces took this doctorine that any amount of risk is too much then they simply would be unable to operate.
There has to be a certain amount of acceptable civilian risk and that should be proportional to the threat you are attempting to stop.
Just to clarify, I'm not advocating that Israel is taking acceptable risks. But I am advocating that those risks will always exist with ANY police or military action and the primary debate is over where the red line of acceptable/unacceptable is.