From our friends at Jewish Voice for Peace:
Jewish Voice for Peace (JVP) calls for an immediate cessation of the air strikes and naval bombardment into Gaza and an end to the ongoing siege of Gaza. JVP urges Israel not to exploit its asymmetric power to exacerbate the instability in the region. We urge President Obama to take a stand against these attacks and to use the power of the United States to insist that Israel pursue all diplomatic measures possible for the sake of life, safety and security on all sides. JVP also urges the end of rocket attacks from Gaza into civilian communities in Israel, which we believe is never justifiable, and which only serve to derail efforts for a just resolution to the conflict.
You can find their actions for Gaza and further resources here.