Israeli aircraft on Sunday bombed an empty Palestinian police station in the centre of the Hamas-ruled Gaza Strip, witnesses said, hours after Israel vowed to respond to militant fire.
There were no reports of casualties or injuries in the strike on the building.
An Israeli security official said "the air force has carried out several strikes across the Gaza Strip."
The action followed a warning from Prime Minister Ehud Olmert that he would deal a "disproportionate" blow to the Islamist movement in response to renewed rocket fire against southern Israel since the end of its 22-day offensive in Gaza.
The onslaught left more than 1,300 Palestinians dead. Thirteen Israelis were killed.
"We've said that if there is rocket fire against the south of the country, there will be a severe and disproportionate Israeli response," Olmert warned at a weekly cabinet meeting on Sunday.
Israel -- which goes to the polls on February 10 -- has been hit by several rockets since the January 18 ceasefire.
"We will act according to new rules that will guarantee that we are not dragged into an incessant tit-for-tat war that will not allow normal life in the south of the country," Olmert said.
"The situation... in recent days has increased in a manner that does not allow Israel not to retaliate in order to make sure that our position... is understood by those involved in the fire.
"The response will come at the time, the place and the manner that we choose."
Defence Minister Ehud Barak said that "Hamas was given a very serious blow and, if necessary, it will be given another blow."
Benjamin Ben-Eliezer, infrastructure minister and a member of Israel's powerful security cabinet, said the Islamists had to pay for each rocket fired.
"We have set a price for each rocket fired and now Hamas has to pay," he told army radio.
Palestinian militants in Gaza fired more than 10 rockets and mortar rounds onto southern Israel on Sunday, wounding one civilian and two soldiers, an army spokesman told AFP.
Hamas slammed the Israeli threats as a "campaign stunt" before the election.
"This is an attempt... to destroy the Egyptian efforts to improve the calm," spokesman Taher al-Nunu said in Gaza.
Next week's election is expected to bring the Israeli right-wing back into power, according to opinion polls.
Olmert, forced to step down in September amid corruption probes, is not standing and his centrist Kadima party -- now led by Foreign Minister Tzipi Livni -- is trailing behind the right-wing Likud of former premier Benjamin Netanyahu.
In the aftermath of the Gaza war, the issue of security has jumped to the forefront of the election campaign.
The Hamas spokesman did not say whether the Islamists who rule Gaza were behind the rocket fire, but called on "all groups to respect the national decision concerning the ground situation in Gaza."
Al-Aqsa Martyrs Brigades, a group loosely linked to president Mahmoud Abbas's Fatah movement, claimed responsibility for firing two projectiles on Sunday.
In all, at least 15 rockets had been fired since mutual ceasefires by Israel and Hamas on January 18 ended Israel's massive three-week onslaught on the territory.
Egypt has been leading international efforts to consolidate the ceasefires into a lasting truce, and Abbas was in Cairo on Sunday for talks on the situation. Hamas officials are also due in the Egyptian capital.
Ahmed Yussef, a senior Hamas member, told AFP that the talks in Cairo were proceeding in a "positive direction," without elaborating.
A senior Israeli defence official would only say that "Israel demands two conditions -- the total cessation of fire and an end to arms smuggling. Israel is only holding talks with Egypt on this issue."
Barak and Tzipi Livni, who are bitterly contesting the upcoming February 10 elections, on Sunday voiced conflicting views on the emerging ceasefire.
"Any thought that we can maintain a calm in the south and more effective action against arms smuggling... without the Egyptians is an illusion detached from reality," Barak said during the cabinet meeting.
But Livni rejected any agreement involving Hamas, which Israel and the United States consider a terrorist organisation.
"A deal with Hamas would give it legitimacy and anyone working towards one with Egypt must understand that," Livni said.
Hamas political supremo Khaled Meshaal on Sunday ruled out any permanent ceasefire until Israel ends a crippling blockade it imposed on Gaza after the Islamists seized power there in June 2007.
But an Israeli official said the Jewish state "is not ready to adhere to any agreement that has a time-limit. We want a deal that will be valid for as long as the sides respect it."