U.N. Secretary-General Ban Ki-mono and U.S. Secretary of State John Kerry announced the deal in a joint statement, saying the truce is scheduled to begin at 8 a.m. Friday, or 1 a.m. ET, and will last for three days.
"During this time, the forces on the ground will remain in place," the statement said.
"This is not a time for congratulations or joy or anything except a serious determination -- a focus by everybody to try to figure out the road ahead," Kerry said. "This is a respite. It is a moment of opportunity, not an end."
The cease-fire should allow aid to reach residents of Gaza. It will also allow for the burial of the dead.
The Gaza Ministry of Health said at least 1,432 Palestinians, including civilians, have died since fighting started July 19. Fifty-nine Israelis have died.