Palestinian militants have been training as the end of the truce nears
Palestinian militant groups in Gaza say they are not expecting a six-month ceasefire with Israel which expires on Friday to be renewed.
The Egyptian-brokered deal began on 19 June but has been tested regularly by Palestinian rocket attacks on Israel and Israeli operations in Gaza.
Israel has said it is in favour of renewing the truce.
The Islamist militant group Hamas says Israel failed to ease its blockade on the Gaza Strip.
Israel said a staged easing of the blockade was halted when Hamas failed to fulfil what Israel says were agreed conditions, including ending all rocket fire and halting weapons smuggling.
Both sides have accused the other of regularly infringing the truce.
There had been much speculation about the possible of the renewal of the ceasefire.
But a statement issued after a meeting of Palestinian factions and Hamas in the Gaza Strip said negotiations were not ongoing as the expiration of the ceasefire neared.
"No mediator has approached us to extend the ceasefire so based on this... [after 19 December] we will respond to any Israeli aggression," the communique said.
Earlier, a Gaza-based spokesman for Hamas, Fawzi Barhoum, said there was "no possibility" of renewing the truce.
"We at Hamas have the right to respond to any Zionist aggression against the Palestinian people. It's a national duty," he said.
Speaking to Israel's Haaretz newspaper, Defence Minister Ehud Barak said the ceasefire had been beneficial.
"Of course the tahadiyeh (calm) was not a mistake," he told Haaretz.
"If the quiet continues, there will be quiet. If the calm breaks, we will operate."
The BBC's Katya Adler, in Jerusalem, says at the moment there has been no mention by Palestinians of escalating the violence.
However, there have been regular outbreaks of violence in recent weeks.
Palestinian armed factions have fired more than 40 rockets at Israel over the Gaza border this week, according to Israel's military.
No-one was killed but a number of people were injured. Israel has responded with airstrikes, killing one Palestinian.
Mr Barak has spoken of a possible ground invasion, our correspondent says, but made it clear he sees no urgency.