The initial 12-hour cease=fire expired 8 p.m. Saturday, 1 p.m. ET.
Israel agreed to another four hours of truce to give diplomats extra time to work on a longer agreement, but moments after the end of the first cease-fire, rockets fired from Gaza hit Israel. There were no injuries reported in that attack.
Hamas spokesman Abu Zuhri said no to an extension.
"There won't been any talks about extending the cease-fire as long as there aren't talks about breaking the siege," said Israa Al-Mudalal of the Gaza Ministry of Foreign Affairs.
Israeli officials told CNN the United Nations has asked for 24 hours of peace for negotiations.
"We owe to the people of both Israel and Gaza our renewed effort to consolidate this pause in fighting into a more sustainable cease-fire," U.S. Secretary General Ban Ki-moon said in a statement, calling for a week-long humanitarian ceasefire.
The cease-fire allowed Palestinians to return to their homes and remove bodies from rubble. More than 100 bodies were removed that had previously been too difficult to access, Dr. Ashraf al-Qedra from the Gaza Ministry of Health said.