The Israeli assault, which was designed to curb militant rocket attacks from the Palestinian enclave and lasted from December 27 to January 18, killed some 1,300 Palestinians, injured more than 5,300, and caused widespread damage and destruction, the UN said.
"With the help of this $613 million appeal, the United Nations and other aid agencies can jump into action to help the 1.4 million civilians in the Gaza Strip to recover," Secretary General Ban Ki-moon said at a news conference during the World Economic Forum in Davos, Switzerland.
The appeal will cover requirements of the UN and other aid agencies for the next six-to-nine months and cover critical items such as food, water, sanitation, health care and shelter, as well as support basic services, such as education, the organization said.
The funds will also help to remove the debris of war, including unexploded ordnance, finance emergency repairs for basic infrastructure, and provide psychological help for the victims. An appeal for longer-term needs will be launched later.
Ban, who visited Gaza earlier this month, said the region could face a greater humanitarian disaster if action was not taken immediately.
John Holmes, the under secretary general for humanitarian affairs and emergency relief coordinator who recently returned from a needs assessment mission to Gaza, reiterated his appeal to Israel to open up border crossings into Gaza and ensure full access for aid supplies.
Exchanges of fire have continued between Israel and Gaza since the two sides announced separate ceasefires on January 18, putting the truce in danger.