It's an idiotic cycle of tit for tat retribution, and unless Israel strikes at the root of the problem, the branches will simply grow back. While Iran is a major backer and instigator of this mess, knocking out Syria would deflate Hamas and Hizbullah and cause them to have to travel hundreds of miles to find safe haven. The Israeli army should push into and lay seige to the area around Damascus, eradicate the Ba'athists, topple the government, and then leave.
Leaving, that is, with a stated threat: We don't care who's in power in Syria, so long as they leave us alone. We can and will come back and slaughter your government, and will do so unless it's one that will live with us in peace.
Israel's military, like ours, will do far better against a standing army than scattered insurgents. So let them.
As long as Syria's government is free to wage proxy war against Israel, Israel will never know peace. Period. Anything they do against Hamas and Hizbullah will produce temporary gains, and permenant losses, unless they take out the lifeline that keeps them alive.
The ultimate address remains Damascus of course. But Israel does not want outright war at this point. It has plenty of means of sending the Syrians a message. The IDF has contained Lebanon by cutting off Hezbollah's supply and escape routes. Now it can slowly grind them up and the Syrians and Iranians can't bring anything in by air or by land because those routes are out. Ditto for the sea. Eventually, Hezbollah's supplies will run out. What's needed in this war is patience and I am confident Israel will know when the decisive blow has been struck.
(The Palestinian terrorist regime is the crisis and Israel's fist is the answer.)