Army helicopters fired missiles, heavily damaging offices connected to the ruling Fatah movement and roads in the northern part of the territory.
The air assault came just hours after Israeli Defence Minister Shaul Mofaz ordered the army to begin assembling a security zone in northern Gaza that Palestinians will be barred from entering.
An opinion poll carried by public television suggested strong Israeli support for a tough line on rocket firings.
The poll conducted by the Geocartographia Institute found that 69 percent of respondents supported "eye-for-an-eye" retaliation against just 17 percent who advocated restraint.
Rocket attacks
Rockets fired from helicopters slammed into the offices of Palestinian leader Mahmud Abbas's party in the northern town of Beit Lahiya, causing serious damage but no injuries.
The Israeli army said the buildings were used by the Al-Aqsa Martyrs Brigades, an armed offshoot of Fatah.
Helicopters also fired weapons at roads and a bridge used to access sites from where rockets are fired, the army added.
"The objective of targeting these routes is to prevent the passage of terrorists to the rocket launching grounds and to disrupt the repeated attempts to fire projectile rockets at Israeli targets," an army spokesman said.
Al-Aqsa claimed to have fired rockets into Israel on Monday, one of which landed near a nursery school but none of which caused any damage or injuries.
The Palestinian Authority criticised the raids, with spokesman Nabil Abu Rudeina saying the attacks compromised a de facto truce that the principal militant factions have largely observed since the start of the year.
"The continued aggression and Israeli raids risk sabotaging efforts made by the Palestinian Authority to consolidate the truce," he said.
Abu Rudeina urged Washington to "act quickly to end the Israeli escalation and overturn the Israeli decision to establish a buffer zone in Gaza".
Three months after Israel withdrew all Jewish settlers and troops from Gaza following a 38-year occupation, Mofaz ordered the army to begin setting up a "security strip" as a buffer zone to protect Israel against militant attacks.
Any Palestinian straying into the zone could be shot by troops from across the border.
Sterile zone
Israeli television said that helicopters would play a key role in enforcing the "sterile" zone, largely to envelop former Jewish settlements.
Mr Mofaz said the idea of a ground operation into Gaza was "not an issue at the moment" but said the army would be fully prepared for any action it deemed fit.
"We have many other means at our disposal that we can put into operation in order to limit and stop the firing of rockets," he told public radio.
An Israeli military source told Agence France Presse that movement to enforce the security zone could come in the "next few days", with talks still underway to determine logistics.
"Exactly what this zone or strip will be is still being decided upon" in talks within the army and defence ministry, the source said.
After a security meeting on Thursday, Prime Minister Ariel Sharon ordered the army to establish the no-man's land.
Local media had reported that the army was awaiting an improvement in the weather before starting to enforce the area, albeit without reoccupying the territory with ground troops.
Palestinian Prime Minister Ahmed Qorei has "categorically rejected" the plans and warned against "the consequences" of the security buffer zone.
Given the somewhat less than watertight Palestinian truce, an upsurge in violence is predicted ahead of parliamentary elections in January.
In further evidence of the heady chaos in Gaza, around 30 Fatah gunmen seized the premises of a local authority building in Beit Lahiya, demanding jobs in the rebranded Palestinian security services.
Abbas urges calm
Palestinian leader Mahmoud Abbas urged militant factions to halt rocket fire and renew a truce that expires at the end of the year.
But militant leaders who met Abbas in Gaza blamed Israel for the violence and said there was little chance they would continue their commitment to the informal ceasefire into the new year.
"We are calling on all sides to be committed to calm," top Palestinian negotiator Saeb Erekat told reporters after the late night meetings. "We regard calm as in the higher interest."
A leader of Islamic Jihad, which has carried out suicide bombings despite the truce, said he did not believe there would be an extension to the "period of calm" that militants agreed to follow at a Cairo summit.
"When the time is up there will be a general position, but calm will most likely not be extended," said Khaled al-Batsh.
US regrets zone
The US said it regretted plans by Israel for a "security zone" in the Gaza Strip but said the move was prompted by Palestinian militant rocket attacks.
"I would characterise it as something that we wish were not taking place, but see it in the context of ongoing attacks and failure to address the security problem," US State Department spokesman Adam Ereli said.
"Israel is responding to Qassam rockets being fired on its territory from Gaza. That is a big problem," Mr Ereli said.
"And what we would really like to see, frankly, is effective action against those responsible for such attacks so that this kind of measures that Israel is taking are not necessary," he said.
"This ongoing 'tit for tat' just underscores in our view the urgent need for effective action against enemies of the peace process and enemies, frankly, within the Palestinian people," Mr Ereli said.
Lebanon rockets
Meanwhile seven Katyusha rockets have been fired at north
Israel from southern Lebanon, Lebanese security services said.
No one immediately claimed responsibility.
Late Tuesday Israeli security sources said at least three Katyusha rockets slammed into Israeli territory after being fired from Lebanon. There were no reports of casualties.
The Israeli town of Kiryat Shmona close to the border with Lebanon came under attack and electricity supplies were cut, they said.
Witnesses said that two houses were hit by a rocket. Local people were told to go down to shelters.
Explosions were also heard at Shlomi, a small town in western Galilee, Israeli radio reported.
Last month four Hezbollah fighters were killed and 11 Israeli soldiers wounded in fighting on the border between Israel and Lebanon.