What's going on in Gaza is terrible, but it's not genocide. What's going on in Syria, Iraq, Sudan, Congo and Somalia are examples of genocide.
There's no excuse for the deaths of this many civilians, but it's not as if Israel has unilaterally decided it's time go on a murderous rampage. Unless I'm mistaken the current framework for the ceasefire that Egypt proposed stipulates that if Hamas stops firing rockets into Israel with the express purpose of killing civilians, all hostilities would stop?
There are clearly underlying issues which need to be addressed, the least of which are the blockades, but if all I have to do to stop the deaths of this many people is to lay down my weapons and accept a ceasefire, what reasons would I have not to?