U.S. Secretary of State Hillary Clinton has met Egyptian President Muhammad Morsi in Cairo to discuss a possible truce in Gaza, while a bus blast in Tel Aviv injured at least 17 Israelis.
Prime Minister Benjamin Netanyahu's office described it as a "terrorist attack."
Police said the explosion was caused by a bomb placed on the vehicle. It occurred near the Defense Ministry and military headquarters.
It was the first bombing in Tel Aviv since 2006. While Hamas did not take responsibility for the attack, it praised the bombing.
The White House denounced it as "outrageous" and reaffirmed the United States' "unshakeable commitment to Israel's security."
Clinton is in the region to boost Egyptian-led efforts to broker a truce between Israel and militants in the Hamas-ruled Gaza.
Clinton met with Palestinian Authority President Mahmud Abbas in the West Bank earlier on November 21 and held a second meeting in Israel with Prime Minister Netanyahu.
Calling For Negotiations
UN chief Ban Ki-moon also arrived in Cairo after holding separate talks with Abbas in the West Bank capital of Ramallah earlier the same day.
Speaking after his talks with Abbas, Ban urged Hamas to return to negotiations.
"I reiterate my call for an immediate cessation of indiscriminate rocket attacks by Palestinian militants targeting Israeli populated centers," Ban said. "This is unacceptable. Now is the time for diplomacy."
However, Hamas spokesman Sami Abu Zuhri, speaking in Gaza City, said the only way to stop rocket attacks was through negotiations.
"Up until this moment there has not been any cease-fire agreement and until a cease-fire is agreed upon, we will continue to respond to the Israeli crimes," Zuhri said.
"Especially since the occupiers are concentrating on targeting women and children, we affirm that we will respond with the same, as long as the occupiers continue to target our families in Gaza."
Israeli strikes on November 21 targeted some 100 sites in Gaza, and Hamas hit southern Israel with four rockets.
At least 146 Palestinians -- mostly civilians -- and five Israelis have been killed in the weeklong conflict.
With reporting by dpa and AP