JERUSALEM (AFP) - Israel's aerial bombardment of Gaza claimed its 105th Palestinian life on Friday as Hamas pounded central Israel with rockets and Washington offered to help broker a truce.
Diplomatic efforts to end the hostilities gathered pace, with US President Barack Obama phoning Israeli Prime Minister Benjamin Netanyahu.
"The United States remains prepared to facilitate a cessation of hostilities," the White House said.
But Mr Netanyahu remained resolute, saying he would not end his campaign until he achieved his goal of stopping the Hamas fire.
"No international pressure will prevent us from striking, with all force, against the terrorist organisation which calls for our destruction," he told a news conference in Tel Aviv. "No terrorist target in Gaza is immune."
World leaders "understand the need to act", he said.
Sparking fears of an expanded conflict, at least one rocket fired from Lebanon hit open ground in northern Israel early Friday. Despite international concerns, truce efforts were unsuccessful, according to Cairo, which has been key in mediating previous Hamas-Israel ceasefires.
"Egypt has communicated with all sides to halt violence against civilians and called on them to continue with the truce agreement signed in November 2012," the foreign ministry said. "Unfortunately, these efforts... have met with stubbornness."
After weeks of rocket fire on its south, Israel appeared bent on dealing a fatal blow to the Islamist Hamas. Ismail Haniya, Gaza's former premier and the most senior Hamas official in the coastal enclave, also ruled out any end to hostilities. "(Israel) is the one that started this aggression and it must stop, because we are (simply) defending ourselves," he said.
Israel says preparations are under way for a possible ground attack, with tanks and artillery massed along the border and some 33,000 reservists mobilised out of 40,000 approved by the cabinet. Foreign Minister Avigdor Lieberman said he expected a political decision on a possible ground operation within 48 hours.
"At the moment we are dealing with the first phase... air attacks," he told Channel One television. "I imagine we shall decide tomorrow (Saturday) or the day after on the next stage."
Hamas's armed wing, the Ezzedine al-Qassam Brigades, kept up a steady stream of rocket fire on Israel throughout Friday. Five rockets were shot down over Tel Aviv by the Iron Dome anti-missile system, the army said. The Brigades claimed their militants had targeted Israel's main international airport near the city. Ben Gurion Airport closed briefly but then resumed normal operations.
Hamas warned "all foreign airlines" to halt flights because of "the dangers surrounding all the airports due to the ongoing war". As a result of the rocket fire from Lebanon, a Polish airliner bound for Tel Aviv was forced to make an emergency stop in Cyprus, before returning to Poland, aviation authorities said. In Gaza, 13 Palestinians, including a woman and seven-year-old child, were killed in separate Israeli air strikes on Friday, hiking the overall death toll to 105, medics said. More than 500 people there have been wounded.
So far, no one in Israel has been killed. Two have been seriously wounded, including a man at a petrol station hit by a rocket.
The army said a woman was injured late Friday when a rocket scored a direct hit on a house in the southern city of Beersheva. It did not elaborate, but army radio said that the 80-year-old was slightly hurt.
In northern Israel, at least one rocket fired from Lebanon struck an open area near Metula, prompting troops to hit back with artillery fire, the army said. The military believed a Palestinian group had fired in solidarity with Hamas, public radio reported, as fears grew the violence in Gaza could spread to other fronts.
The army has confirmed hitting 21 Hamas-owned structures in 24 hours, prompting a warning from the UN's human rights office over the number of civilian casualties from strikes on homes. "Even when a home is identified as being used for military purposes, any attack must be proportionate... and precautions must be taken to protect civilians," said spokeswoman Ravina Shamdasani.
A group of 34 charities and NGOs also called for an end to the fighting. "Military actions by all parties must stop," said a statement signed by groups including ActionAid, CARE, Oxfam and Save the Children. Amnesty International called for the United Nations "to immediately impose a comprehensive arms embargo on Israel, Hamas and Palestinian armed groups" and launch an inquiry into "violations committed on all sides".
Since the start of Israel's operation on Tuesday, "at least 500" rockets have struck the Jewish state, and Iron Dome has shot down around 130, an army spokeswoman told AFP. Of those, more than 90 have hit Israel since midnight on Thursday, and 22 were intercepted, the army said.