The head of the Palestinian group Hamas has met with officials in Egypt on the conflict with Israel around the Gaza Strip.
Khaled Meshaal was due to hold talks with Egypt's intelligence chief, as well as Turkish Prime Minister Recep Tayyip Erdogan.
Erdogan said Israel should answer for what he called a "massacre" in Gaza, where dozens of Palestinians have been killed by Israeli air strikes in the past four days.
In Washington, the White House called for a "deescalation" of the Gaza violence but defended Israel's right to self-defense.
Palestinian officials in Washington criticized the U.S. response as "biased and weak," saying Israel started the escalation with a missile strike on November 14 that killed Hamas military chief Ahmed al-Jaabari.
Close to 40 Palestinians and three Israelis have died in the violence.
Tunisian Foreign Minister Rafik Abdesslem visited the Gaza Strip on November 17 as fighting continued.
Abdesslem denounced Israeli air strikes on the Palestinian enclave as unacceptable and against international law.
"There is an international law and there is international restrictions and what Israel is doing is unacceptable and illegal," he said. "Israel should understand that many things have changed and that lots of water has run in the Arab river and it should recognize that it is not totally free and not totally fortified and it is not above the international law."
He is the second Arab official to visit in two days, following a visit by Egyptian Prime Minister Hisham Qandil on November 16.
Israeli Defense Force (IDF) spokeswoman Avital Leibovich told reporters in Jerusalem that Israel is determined to end the rocket fire from Gaza.
"Today we see many of Hamas senior militant leaders in hiding, hiding places but in civilian places, such as mosques, and hospitals," she said. "This all brings us to the assumption that Hamas is under great pressure as a result of the IDF targeting. We are determined to continue with this operation until we bring some peace and quiet and normality to 3 million Israelis which are currently under immediate rocket danger."
Israel's cabinet called up 75,000 members of the armed forces reserves on November 16 as the Jewish state masses troops along the border with Gaza for what many expect will be a ground operation.
Australian Foreign Minster Bob Carr urged both Israelis and Palestinians to exercise restraint.
"Talk is the alternative to rockets being fired and to retaliatory ground action," Carr said in Sydney. "Don't disparage talk. This would be a whole lot healthier -- the whole Middle East -- if the two sides were at a table talking to one another, talking about the resolution of the final status issues that enables as a fundamental outcome a Palestinian state side by side with a secure Israel. We've got to keep returning to those fundamental."
Iran's Defense Minister Ahmad Vahidi said on November 17 that the Muslim world should unite against Israel. The official IRNA news agency quotes him as saying that "putting an end to the Zionist regime's crimes is only possible through a united, revolutionary retaliation by the Muslim world."
Israel launched a concerted air campaign against the densely populated Gaza Strip on November 14 with the stated aim of halting regular rocket fire out of Gaza that has disrupted life across southern Israel.
Palestinian militants have fired hundreds of rockets in the last three days, reaching Tel Aviv and Jerusalem.
With reporting by Reuters, AFP, AP, and dpa