U.S. President Barack Obama on Friday reiterated U.S. support for Israel's right to defend itself during a call with Israeli Prime Minister Benjamin Netanyahu about the conflict in Gaza.

"The president reiterated U.S. support for Israel's right to defend itself, and expressed regret over the loss of Israeli and Palestinian civilian lives," the White House said in a summary of the conversation.

Four Palestinians were killed in new Israeli air strikes on central Gaza Saturday, raising the death toll from 72 hours of raids to 44, the emergency services said.

A statement first announced two deaths in a strike on Deir al-Balah, then added an additional two deaths in a strike on the Masdar area, also in central Gaza.

U.S. President Barack Obama and Turkish Prime Minister Recep Tayyip Erdogan expressed concern Friday that renewed violence in Israel and the Gaza Strip would damage the Middle East peace process.

"The two leaders shared their concerns about the dangers to civilian populations on both sides and expressed their common desire to see an end to the violence," the White House said, after Obama called the Turkish leader.

Tunisia has condemned Israel's strikes against the Gaza Strip and has sent its foreign minister to visit the embattled Palestinian territory.

Rafik Abdessalem is set to arrive in Gaza on Saturday with a delegation carrying humanitarian aid.

Turkish Prime Minister Recep Tayyip Erdogan on Friday accused Israeli officials of having ordered the air strikes on the Gaza Strip that left 23 Palestinians dead as an electoral move ahead of January's general election.

"Once again this time, they're on the eve of an election," Erdogan told reporters, recalling Israel's "Cast Lead" Gaza offensive which began just six weeks before the 2009 election.

The U.N.'s top human rights official has denounced three days of fierce clashes between Israeli forces and Gaza militants, urging them both to pull back.

U.N. High Commissioner for Human Rights Navi Pillay says she is appalled that civilians are being killed, including three Israelis in their apartment and several Palestinian children, including a baby, and a pregnant woman.

Hamas militants from the Ezzedine al-Qassam Brigades on Friday executed a man on charges of "collaborating" with Israel as warplanes pounded Gaza, Palestinian sources said.

"The Qassam Brigades on Friday executed a collaborator for providing guidance and information on the locations of the resistance and their rocket launchers to the Israeli occupation," a source told Agence France Presse on condition of anonymity.

Speaker Nabih Berri urged on Friday the various heads of parliaments and unions to pressure Israel to end its assault against the Gaza Strip.

He called in a letter to the various presidents for holding emergency sessions “in order to launch a parliamentary campaign to pressure Israel to halt its aggression against the Palestinian people.”

Demonstrations against Israel's military action in Gaza and in support of Palestinians took place in Tehran and 700 other Iranian cities after Friday Muslim prayers, news agency ISNA said.

Protesters chanted "death to America" and "death to Israel" in the capital, in demonstrations called for by the authorities.

French President Francois Hollande said Friday he was seriously concerned by the escalation of violence in the Gaza Strip and had spoken to Israeli and Egyptian leaders a day earlier.

"I am seriously concerned by what is happening in the Gaza Strip, both by the rocket attacks on Israel and the reprisals that this escalation may bring," Hollande told reporters at a joint press conference with Poland's President Bronislaw Komorowski, who called for a resumption of peace talks between Israel and the Palestinian Authority.