Having said that I believe that every country in this world owes it's citizens the right of protection, so if an external force attacks them in their territories, they have the right to defend and respond in equal terms. So on that I can not blame the IDF for responding to the killings and threats on their citizens, because if they don't greater calamity from the enemy can befall on them.
Palestinians aren't an "external force" in their own country that is currently occupied! That would be like saying "Russia has the right to defend itself inside Ukrainian soil that they occupy"!!!
The Zionists are the "external force" that are occupying the Palestinian soil and killing people of Palestine. According to the international law and the United Nations charter nothing can impair the right of Palestinians from using any means necessary to fight against the invaders that are committing genocide in their lands. Be it in occupied Palestinian lands like Quds or the semi-occupied regions such as Gaza and West Bank.
In other words the Zionist regime, ie. Israel, doesn't have any right to even be there let alone use any force against the Palestinians (whether civilians or the armed forces defending them such as Hamas).