In a statement issued Tuesday through the Carter Center in Atlanta, the former president also said that both sides in the conflict must distinguish between combatants and noncombatants.
Carter said Israel must ensure that its use of force is "proportionate in accordance with international humanitarian law."
The statement said Gaza is on the brink of a humanitarian crisis.
Fighting in the past two weeks has killed more than 570 Palestinians and two dozen Israelis.
President Obama said Monday that the international community must focus on bringing about a cease-fire that ends the killing of civilians on both sides of the conflict.
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