Hamas has said it will not sign a peace deal with Israel that fails to meet the demands of its people.
Khalil al-Haya, the Palestinian group’s negotiator at the talks in Egypt seeking to stop fighting in Gaza, said on Thursday they were negotiating with a "difficult side versed in procrastination".
"We are keen on having an agreement concluded. It must satisfy the demands of our people," said Haya during a public address in which he briefed the people of Gaza on the progress of the talks.
Haya said Hamas would continue to demand the end of what he called "unjust incursions" and a "permanent lifting" of the siege imposed by Israel on Gaza in 2006.
The comments came hours after the truce between Hamas and Israel was extended for five days as negotiators from both sides press ahead with the talks in Cairo.
Members of the Palestinian delegation said they would return to Cairo on Saturday night to begin more talks on Sunday.
Egyptian and Palestinian sources told the Reuters news agency Israel had tentatively agreed to allow some supplies into Gaza and relax curbs on the cross-border movement of people and goods, subject to certain conditions.
"It was a war of necessity not a war of choice. We had no choice but to defend ourselves," Haya said.
"We are united and are unified in blood and dead bodies. We are one front, one side, one body ... We are all enaged in one battle defending our people. The war is the beginning of liberation."
Al Jazeera’s Andrew Simmons, reporting from Gaza, said Haya was vague about the precise stage the talks have reached.
A renewed truce between the two sides appeared to be holding despite a shaky start.
The Israeli military on Thursday said fighters in Gaza breached the truce and fired eight rockets at Israel and that in response, aircraft targeted multiple "rocket launchers and terror sites" across the enclave.
Hamas official Izzat Reshiq denied the Palestinians had breached the truce, and denounced Israel's air strikes as "a violation of the calm".
No casualties were reported in any of the incidents, and hostilities had ended by dawn.
A halt in more than a month of fighting, in which 1,945 Palestinians and 67 Israelis have been killed, had been set to expire at midnight on Monday.
If it holds, the five day ceasefire will be the longest period peace since hostilities began.
The violence is the deadliest since the two sides fought a three-week war in the winter of 2008-9.
At the last minute, the Palestinians announced the truce extension so both sides could work out a long-term ceasefire, mediated by Egypt.
"Israel has accepted the ceasefire extension," said an Israeli official, speaking on condition of anonymity.
Bridging the gaps between Israel and the Palestinians in order to secure a permanent ceasefire has proved to be difficult.
"It is the first time we have a five-day ceasefire. The previous ones have been three days. It has been a rocky start," reported our correspondent.
"The negotiations went right up to the wire before the Palestinians made their announcement," he added.
"Then, within a few minutes, there was rocket fire on the Wednesday night, and then early into Thursday, in the first three minutes of the ceasefire, there were at least three rockets entering Israeli territory and the response was at least three airstrikes by the Israelis ... We have since then what appears to be a ceasefire."
Hamas leader Ismail Haniyeh told Al-Aqsa Hamas television on Wednesday that the group would insist on "lifting the Gaza blockade" and reducing movement restrictions on the territory's 1.8 million residents, as a prerequisite to a "permanent calm".