Two rockets were fired from south Lebanon towards the Israeli border on Wednesday evening, a Lebanese security official told Agence France Press.

"Two rockets were fired, one fell in what was clearly Lebanese territory, the other went towards Israel," the official said on condition of anonymity. It was not immediately clear where the second rocket fell.

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.

A ceasefire came into effect Wednesday in and around Gaza after a week of cross-border violence between Israel and Palestinian militants that killed at least 160 people.

Gaza City's streets were dark and deserted in the minutes after the ceasefire began at 1900 GMT, and Israeli drones could be heard overhead, but soon after people poured out onto the streets to hail the "victory."

The United States condemned a bus bombing that injured 17 people in Tel Aviv on Wednesday and undermined attempts to mediate a ceasefire in Gaza, branding it a "terrorist attack."

"These attacks against innocent Israeli civilians are outrageous," the White House said, reaffirming Washington's "unshakeable commitment to Israel's security and our deep friendship and solidarity with the Israeli people.

U.S. Secretary of State Hillary Clinton arrived in Cairo on Wednesday for talks with Egyptian President Mohammed Morsi, an airport official said, amid ongoing efforts to reach a truce deal in Gaza.

She is expected to go straight into a meeting with her Egyptian counterpart Mohammed Kamel Amr and with Morsi, who is playing a key role in mediating a ceasefire agreement between Israel and Hamas in the Gaza Strip.

Iran has supplied military aid to the Islamist group Hamas in Gaza locked in a conflict with Israel during which it has fired missiles at Tel Aviv for the first time, the parliament speaker said Wednesday.

"We are proud to defend the people of Palestine and Hamas ... and that our assistance to them has been both financial and military," Ali Larijani said without elaborating, in remarks reported by parliament's website, ICANA.ir.

The March 14 general-secretariat warned on Wednesday against any “adventure” that would open a new front in southern Lebanon in light of the Israeli aggression on the Gaza Strip.

Following its weekly meeting, the general-secretariat announced in a statement “full solidarity with the Palestinian people that are being targeted by Israel and paying the price of its brutality.”

U.N. chief Ban Ki-moon called for an immediate halt to rocket attacks on Israel from the Gaza Strip, after talks with Palestinian President Mahmud Abbas on Wednesday.

"I reiterate my call for an immediate cessation of indiscriminate rocket attacks by Palestinian militants targeting Israeli populated centers. This is unacceptable," he told a news conference in the West Bank city of Ramallah.

A bomb blast ripped through the front of a crowded commuter bus as it passed the Israeli defense ministry in Tel Aviv during rush hour on Wednesday, injuring 17 people.

A spokesman for Prime Minister Benjamin Netanyahu said Israel had been hit by a "terrorist attack," with Washington calling it "outrageous" and Russia branding it as "criminal".