Calling a weekend barrage of rockets and mortar shells on southern communities a "fundamental violation" of the five-month cease-fire with Hamas, Prime Minister Ehud Olmert said the government would continue to step up pressure on Hamas by keeping Gaza border crossings closed and other unspecified means. Olmert convened emergency security consultations in Tel Aviv with Defense Minister Ehud Barak, IDF Chief of General Staff Lt.-Gen. Gabi Ashkenazi and other senior security officials on Friday night, in response to 16 rockets and a mortar shell fired by Gazans earlier in the day. Five of the rockets were Grad-type Katyushas. Barak, who had earlier visited Sderot, said the defense establishment would continue to act to protect residents of the South and IDF soldiers. He added, however, that "if the Gaza factions want to resume the truce, we will consider it in a positive light." Earlier on Friday, senior officials in Jerusalem said that if Hamas stopped firing rockets immediately, the truce could be reestablished. However, they warned that if the attacks continue, Israel's response would be "harsh and painful." Foreign Minister Tzipi Livni, speaking Saturday night at a UJC Lions of Judah conference in Tel Aviv, said Israel would not put up with "repeated breaches of the cease-fire" on the Gaza border, warning that "if Israeli civilians are attacked, Israel will respond in force to protect them." Alluding to Hamas, she warned that "there are times when Israel must say: 'Enough is enough.'" Though Israel was "not interested in causing a deterioration in the situation, we can't put up with repeated breaches of the cease-fire," she said, "if there is quiet, and [Hamas] doesn't use that time to prepare for the next attack, they will have quiet in return." Industry, Trade and Labor Minister Eli Yishai called for an urgent security cabinet meeting to discuss the rocket attacks in the South. "In practice, there is no truce, and we cannot tolerate a situation in which Sderot and Gaza-periphery residents are abandoned," Yishai told Army Radio. "There is a deterioration that must be dealt with," he added. While the Gaza situation is escalating, Olmert will meet in the capital on Monday with Palestinian Authority President Mahmoud Abbas, officials in Jerusalem have confirmed. Diplomatic sources said the meeting would be a continuation of the contacts held between the two men over the past year as part of the Annapolis process and the efforts to narrow the gaps between the two sides. The contacts will continue even though both sides have acknowledged that the deadline set by Washington, to clinch a peace agreement before President George W. Bush leaves office, will not be met. Senior Palestinian negotiator Saeb Erekat said on Saturday the two leaders would discuss the flare-up of violence in Gaza. However, Abbas has had little influence over events in Gaza since the Hamas takeover of the Strip in June 2007. Erekat also said Abbas would again raise Palestinian concerns over settlement activity in the West Bank. The ongoing closure of the border crossings into Gaza has prompted international criticism. UN Secretary-General Ban Ki-moon called on Israel to open the crossings to humanitarian aid. He also condemned the rocket fire on Israel. Measures that increase the suffering of Gaza's civilians "are unacceptable and should cease immediately," he said in a statement. On Friday, the EU commissioner for external relations, Benita Ferrero-Waldner, issued a statement expressing profound concern over the consequences for Gazans of the closures for deliveries of fuel and basic humanitarian assistance. She called on Israel to reopen the border for humanitarian and commercial supplies and to resume fuel deliveries for the Gaza power plant. "International law requires the provision of access to essential services such as electricity and clean water to the civilian population. Recent infringements of the 'calm' agreed in June must not lead to a renewed cycle of violence. I call on all parties to exercise restraint," the EU commissioner said. Haviv Rettig contributed to this report.