The Israeli public security minister, Avi Dichter, said that could mean increased ground, and air operations or actions by special forces.
Key diplomatic players
Palestinian officials are engaged in efforts to form a national unity government to include Hamas and Fatah.
This would be expected to result in the lifting of a Western blockade on financial aid to the Palestinian Authority, in place since Hamas came to power in March.
Representatives of the so-called quartet of Middle East diplomatic players were also due to meet in Cairo on Wednesday to discuss a response to a unity government.
"The aim of this meeting is to come up with a common analysis of the situation and consider the next move, in particular if and when the Palestinians form a national unity government," Marc Otte, the European Union Middle East envoy, said.
The quartet meeting was to be attended by David Welch, the US regional envoy, as well as his counterparts Alvaro de Soto and Sergei Iacovlev from the United Nations and Russia.
"One of the main issues will be how to respond to a national unity government," one UN official said.
"This response is clearly very important because there is no sense in a unity government if it doesn't lift the blockade."
Otte said he and his counterparts would also attempt to seal a quartet meeting at the ministerial level by the end of the year.
"We need to have a more sustained working relationship without partners in the region," Otto said, referring to Israel and a grouping of Arab governments.
The quartet drafted the roadmap peace plan which has very little progress since its launch in 2003.
De Soto, who met with Amr Moussa, the Arab League secretary-general, before Wednesday’s quartet meeting, said the United Nations was "encouraged" by the ongoing efforts to form a Palestinian unity government.
"A better position than the current one to bring about a better engagement with the international community and also better address the problem of law and order in the Palestinian streets,” he said.
Ahmed Ben Helli, the Arab League deputy chief, has hit out at the quartet for not doing enough to rein in the deadly offensive launched by Israel after the capture of a soldier by Gaza-based militants in June.
"It is quite clear that the message of dissatisfaction in what the [UN] Security Council was able to do was felt rather strongly," de Soto said.
The Cairo quartet meeting comes after an Israeli shelling of the northern Gaza Strip town of Beit Hanoun last week which killed 19 Palestinians, mainly women and children.
"We hope that Israel will not only investigate the military operational aspect of the actions it took ... but also pause and take a long hard look at the whole policy of strong actions which is obviously not achieving the desired results," said de Soto.
On Sunday, the US vetoed an Arab-sponsored draft resolution in the Security Council that would have condemned Israel's deadly attack.
Israel and the US signalled a willingness Monday to talk to the Palestinian government if it moderates itself, though each said they would wait to see the new government's programme before they passed judgment.
In Jerusalem, US diplomats said they have been in close contact with Abbas over his attempts to assemble the new government.