Israel's Defense Minister Ehud Barak, a close ally of Prime Minister Benjamin Netanyahu, stunned observers on Monday by announcing his retirement from politics ahead of snap elections in January,

The decision appeared to end a decades-long career that has seen him serve in top governmental posts and lead the country as prime minister.

A poll shows about half of Israelis think their government should have continued its military offensive against Palestinian militants in Hamas-ruled Gaza.

The independent Maagar Mohot poll released on Friday shows 49 percent of respondents feel Israel should have kept going after squads who fire rockets into Israel. Thirty-one percent supported the government's decision to stop. Twenty percent had no opinion.

Israel and the United States have agreed to work together to prevent the smuggling of weapons from Iran to militant groups in the Gaza Strip, Prime Minister Benjamin Netanyahu said on Wednesday.

"Israel cannot sit idly by as its enemies strengthen themselves with weapons of terror so I agreed with President (Barack) Obama that we will work together -- Israel and the United States -- against the smuggling of weapons to terror organizations, most of which comes from Iran," he said in a televised address.

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".

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.

At least 20 Palestinians were killed on Tuesday as Israeli air strikes rocked the Gaza Strip, medics in the Hamas-ruled territory said, as a rocket fired by Palestinian militants exploded near Jerusalem.

Two cameramen from Hamas-owned Al-Aqsa TV were among six people killed in a series of Israeli air raids on Gaza City and the north, a Hamas spokesman said.

U.N. chief Ban Ki-moon on Tuesday urged all sides to the Gaza conflict to immediately cease their fire, warning at a news conference in Cairo that an escalation will endanger the whole region.

"All sides must halt fire immediately," Ban said, as an Israeli military operation against rocket-firing militants in Gaza entered a seventh day, with 116 Palestinians and three Israelis killed.

German Foreign Minister Guido Westerwelle will travel to the Middle East on Monday for talks aimed at encouraging a ceasefire between Israel and Gaza militants, his spokesman said.

Westerwelle will meet his Israeli counterpart Avigdor Lieberman in Jerusalem late Monday before seeing Prime Minister Benjamin Netanyahu, President Shimon Peres and Defense Minister Ehud Barak on Tuesday.

Prime Minister Benjamin Netanyahu said on Sunday that Israel is ready to "significantly expand" its operation against militants in the Hamas-run Gaza Strip as it entered its fifth day.

"The army is prepared to significantly expand the operation," Netanyahu said at the start of the weekly cabinet meeting. "The soldiers are ready for any activity that could take place."

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.