U.S. President Barack Obama thanked his Egyptian counterpart Mohamed Morsi on Wednesday for his role is negotiating a planned truce between Israel and Palestinian militants in Gaza.

"The president thanked President Morsi for his efforts to achieve a sustainable ceasefire and for his personal leadership in negotiating a ceasefire proposal," the White House said in a statement.

Palestinian refugees living in Lebanese camps celebrated Wednesday after a bomb ripped through a bus in Tel Aviv injuring 17 people, camp residents told Agence France Presse.

In Nahr al-Bared camp in north Lebanon muezzins sang out words of praise to God via their megaphones, while fireworks lit the sky and fighters handed out sweets, residents said.

U.S. Secretary of State Hillary Clinton said in Jerusalem on Tuesday during Israel's conflict in Gaza that Washington's commitment to the Jewish state's security remains "rock solid."

But the top U.S. diplomat also stressed that Washington expected a quick de-escalation to a seven-day conflict that has shaken the already volatile region and now threatens to spill over into an all-out ground war.

U.S. President Barack Obama called Egyptian President Mohammed Morsi for the third time in 24 hours on Tuesday and "commended" his efforts to secure a truce in Gaza, the White House said.

"He commended President Morsi's efforts to pursue a de-escalation" in the Gaza Strip, deputy national security adviser Ben Rhodes told reporters traveling home from Asia with Obama during a stopover in Japan.

Two cameramen from Hamas-owned Al-Aqsa TV were among six people killed in Israeli air raids on the Gaza Strip, raising Tuesday's death toll to 20, a Hamas spokesman said.

Health officials said a total of more than 125 people had been killed and over 1,000 wounded since Israel began its relentless bombing campaign on November 14 in a bid to stamp out cross-border rocket fire by militants.

Israeli Prime Minister Benjamin Netanyahu told Gaza's Hamas leaders to choose between peace and "the sword" on Tuesday as a diplomatic push intensified to end a week of violence in and around the strip.

"Our hand is outstretched in peace to those of our neighbors who want to make peace with us," Netanyahu said in a statement.

Gunmen executed six "collaborators" in a Gaza City neighborhood on Tuesday, witnesses told AFP, adding that notices were pinned to their bodies saying they had been killed by Hamas's armed wing.

"Gunmen in a minibus pulled up in the neighborhood, pushed six men out and shot them without leaving the vehicle," one of the witnesses said, adding that a message pinned to the bodies read: "al-Qassam Brigades announces the execution of the traitors."

A senior Libyan delegation is to visit the Gaza Strip on Tuesday in a show of solidarity for the Palestinian people under Israeli attack, a government official said.

The source told AFP the team will be led by Salah al-Makhzoum, vice president of the National Assembly, Libya's highest political authority, and deputy prime minister Al-Seddik Krayem.

Egyptian and Hamas officials said they believed they could reach an agreement to end the week-long Gaza conflict on Tuesday but a truce hinged on Israeli assent to a Cairo-mediated ceasefire plan, as U.S. Secretary of State Hillary Clinton arrived in the region to make an urgent push for peace.

The emerging signs of a deal to end seven days of violence that have claimed the lives of 136 Palestinians came as the Israeli army confirmed its first two fatalities from rocket attacks while another missile landed harmlessly just south of Jerusalem.

Hizbullah Leader Sayyed Hassan Nasrallah criticized on Monday Arab countries that “are sending weaponry to Syria but have not aided Gaza with one bullet”, attacking Qatari Prime Minister Sheikh Hamad bin Jassem al-Thani's “sheep” comments.

In a speech he gave on the fifth day of Ashoura, Nasrallah said Arab nations should have contributed in “arming Gaza and supporting its fighters instead of calling for a mediation between it and the Israeli enemy”.