Is the total blockade of the Gaza strip by Israel considered a war crime under international law?

I just want to say that I consider Hamas a terrorist organization, and I’m not a terrorist. I do not, I repeat, I do NOT agree with, or condone, violence in any way, shape or form (this case we’re talking about Hamas). HOWEVER, Israel did some things that are, at best, questionable, and at worst, radical. I would call it a disproportionate retribution. It’s true Gaza is not Israel’s state, and legally it’s not entitled to give the Palestinians food, water, etc. And, it’s true Hamas was elected by the Gaza population, so he is the de facto leader. I’ll even stipulate, though the exaxct specifics I don’t know, that Hamas did more victims than Israel. But he’s not the Palestinians. A quite good portion of Palestinians are not terrorists. That includes newborns and more-than-80-years-olds. Are they considered terrorists too? What’s more, I might add, is that Israel issued an ultimatum in which it intimated the Palestinians on the north to move to the south, to Wadi Gaza. How do we expect not to be a massive death toll because of this? What’s more, all borders of Gaza are closed off, who from Egypt, who from Israel. Lebanon didn’t, as far as I know.

TL;DR What I fear most from this escalation is not about the reaction of Israel to Hamas’ attack on the rave party. It’s about not discriminating the terrorists from innocent civilians (which, by the way, is also a violation of international law), especially when it’s obvious they’re not terrorists.

Anyway, that’s all. The question stands, is serious, and I ask you to give it your best shot, despite the inevitable controversy.