The Aish Hatorah website that pou_bear links to says the following.
Pray for the safety of our soldiers, for the protection of every Jew in Israel, and for the wisdom of our political and military leaders.
Support the I.D.F. by sending goodies, care packages, and letters of support. http://www.thankisraelisoldiers.org/
Undertake mitzvot, good deeds, donations to charity, and Torah learning in the merit of the people of Israel. Judaism teaches that every mitzvah generates merit, and just as you can send your money to wherever you choose, you can send your merit to wherever you choose.”
Of course, all that is true.
However, there is one more thing. Chazal say that Achdus leads to military victory. If there was a way to channel the desire for revenge, the desire to help, etc. into Achdus somehow, it could lead to an actual victory (= destruction of Hamas) rather than “quiet for quiet.”