No international pressure will stop us - Netanyahu

Israeli Prime Minister Benjamin Netanyahu said that he would not bow to international pressure to stop the ferocious military airstrike campaign aimed at crippling Hamas in Gaza.

"No international pressure will prevent us from striking the terrorists who are attacking us," he told a news conference at the defence ministry in Tel Aviv on Friday.

Despite a growing pressure from world leaders to end ceasefire, Netanyahu has vowed to press forward with the attacks which have claimed more than 100 lives.

He also did not rule out the possibility of a ground invasion on Gaza as Israel was reported to have massed thousands of troops along the border for a possible ground operation.

"We are weighing every possibility,” Netanyahu said, according to an AP report.

"I will end it when our goals are realized. And the overriding goal is to restore the peace and quiet.”

On Friday, US President Barack Obama phoned Netanyahu to express concerns and to offer his help in resolving the crisis.

"The United States remains prepared to facilitate a cessation of hostilities, including a return to the November 2012 ceasefire agreement," the White House said, referring to a truce which ended the last major confrontation between Israel and Hamas.

Meanwhile, Egypt, which has played a key role in mediating previous ceasefire agreements, said its efforts were falling on deaf ears.

"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," its foreign ministry said.

"Unfortunately, these efforts... have met with stubbornness."

Israel's allies have backed the country's right to self-defense, but have called for restraint, AFP added.

United Nations Secretary-General Ban Ki-moon has expressed concern about the heavy civilian casualties in Gaza.

Its high commissioner for human rights Navi Pillay said the air campaign may have violated international laws prohibiting the targeting of civilians.

"We have received deeply disturbing reports that many of the civilian casualties, including of children, occurred as a result of strikes on homes."

"Such reports raise serious doubt about whether the Israeli strikes have been in accordance with international humanitarian law and international human rights law," she added.

However, Netanyahu brushed aside these criticisms, defending Israel's aerial campaign is aimed at military targets.

At least 21 Palestinians were killed on Friday, pushing the overall death toll to 106, including dozens of civilians, according to the Health Ministry in Gaza.