There is little doubt that in the 1990-is, Israeli actions against Gaza would be internationally condemned, but this is not the case now. Quite on the contrary, international pressure appears to target Egypt (not Israel), Egyptians are supposed to "stabilize the border situation" aka close the border and participate in the Israeli blockade.
My understanding is, by breaking the Gaza-Egypt fence, Hamas made an important symbolic move. What we have is an explicit demonstration that Egypt cannot be effectively used as a proxy to project the Western (i.e. Israeli) pressure on them.
Whatever legal and diplomatic moves are made, they are still in the state of war with Israel and won't be prevented from doing whatever they want to do.