Palestinian officials said on Sunday Hamas, Islamic Jihad and the al-Aqsa Martyrs' Brigades, had agreed to stop firing rockets if Israel called off its Gaza offensive.
The Israeli offensive was begun last month after Hamas-linked fighters captured a soldier in a raid on an Israeli military post.
The groups denied that an agreement had been reached.
Under the reported deal, the rocket fire was supposed to end at midnight on Saturday. But early on Sunday morning, Palestinians had fired five homemade rockets into Israel, causing no injuries.
Abu Ahmad, an Islamic Jihad spokesman, said no agreement had been reached.
"As long as there is Zionist aggression, we will continue our resistance," he said, adding that talks on reaching an agreement had not ended.
Closed door agreement
The talks in Gaza City were sponsored by Mahmoud Abbas, the Palestinian president, and Ismail Haniya, the prime minister, said officials who spoke on condition of anonymity because the agreement was reached at a closed meeting.
"A cease-fire is a cease-fire. It has to be accepted by the two parties, and it has to lead to a resolution of all the outstanding issues"
Nabil Shaath, an aide to Abbas
Israel has been carrying out a campaign of air strikes and raids into Gaza for nearly a month to pressure armed groups to free the captured soldier and to stop firing rockets into Israel.
More than 100 Palestinians have been killed in the offensive, the majority of them fighters.
Palestinian officials said the unilateral Palestinian cease-fire was meant to end the offensive. But the groups denied that a cease-fire had been reached, calling rocket fire a response to Israeli aggression.
Nabil Shaath, an aide to Abbas, said the president and representatives of armed groups met in recent days and decided that a cease-fire by Israel and the groups was needed.
"A cease-fire is a cease-fire. It has to be accepted by the two parties, and it has to lead to a resolution of all the outstanding issues" in Gaza, Shaath said in an interview.