No, Israel has to fight back when attacked. I support Israel defending itself.
But fighting back by cutting off their water supply? I understand cutting off fuel. I even understand stopping aid temporarily (due to weapons smuggling). But cutting off their water when half of them are kids and then they drink ocean water and get sick... that is not acceptable. Nor is bombing mostly civilian areas to kill a few Hamas members. They need to wait for a clear shot, or storm the place and take out the terrorists without killing the civilians.
On a totally different topic, with IDF assistance Israelis have been slowly taking Palestinian land in the West Bank. Or, maybe that is not completely unrelated.