Yes, the Israeli attacks on Gaza have been disproportionate, brutal and ruthless.  But Hamas must stop firing rockets which give them a pretext.  That would not mean doing nothing.  Someone has to show them that non-violent resistance is effective (though not so macho).  Preferably things that provide photo opportunities – rockets that cover Israelis with flour, for example, or balloons with faces of Israeli politicians.  They can probably think of better ideas.  Look at Danish resistance to the Nazis, for example, or Otpor resisting Milosevic.  Or Gandhi resisting the British, or Martin Luther King.  The situations are not entirely comparable, of course and maybe the enemy not quite so ruthless, but the principle is the same.  It doesn’t provide a pretext for retaliation;  if they don’t retaliate they look foolish, and if they do everyone can see that they have no shred of an excuse.
Use violence and you lose any moral high ground you thought you had – and that applies to both sides.