In fact, we believe - quite rightly - that if the US had conditioned military assistance to Israel on appropriate care for civilians, then the awful tragedy that unfolded in Gaza could have been averted. Similar levers for changing the behaviour of Iran do not exist.
What you saw in Gaza was ALREADY incredible levels of care and restraint (that has cost many Israeli soldiers their lives) to minimize civilian harm, when fighting against an enemy that benefits from increasing said harm.