The United States is to give $US85 million to the U.N. agency providing aid to Palestinian refugees in the West Bank, Gaza, Jordan, Lebanon and Syria.
The announcement was made on Tuesday on the fourth day of the attacks.
The State Department said $US25 million would go to an emergency appeal by the UN Relief and Works Agency for the West Bank and Gaza and the remainder to a general fund run by the agency for Palestinian refugees in the region.
The department said the funds would pay for urgently needed food, medicines and other humanitarian aid.
It called on "all concerned" to protect innocent lives in Gaza and grant the necessary access to aid groups trying to help them.
The statement adds the United States holds Hamas fully responsible for breaking a cease-fire with Israel.