JERUSALEM — Israel will hold back on its new ground offensive in Lebanon until the weekend to give cease-fire efforts another chance, senior officials said today, a day after the government approved a major expansion of the monthlong war.

But prospects for a quick cease-fire resolution by the U.N. Security Council were uncertain, with the United States and France still divided over a timetable for an Israeli withdrawal from Lebanon.

Israeli missiles hit Beirut proper for the first time, damaging a historic lighthouse. Warplanes also dropped leaflets over downtown Beirut, urging residents of three southern suburbs to leave the area. More leaflets were scattered over northern Lebanon, warning trucks off a coastal road linking Lebanon to Syria.

Hezbollah claimed it destroyed 13 Israeli tanks in south Lebanon. The Israeli military declined comment. On Wednesday, 15 Israeli soldiers were killed in Lebanon, the deadliest day for Israeli soldiers in the war. Hezbollah rockets killed a woman and her young daughter, a toddler, in the Israeli Arab village of Deir el Assad, medics said.

The deeper push into Lebanon was approved Wednesday by Israel's Security Cabinet, but a senior government official said today that Prime Minister Ehud Olmert decided to delay the offensive until the weekend. The campaign could begin earlier if Hezbollah launches a major attack on Israel, the official said.

The government's conduct of the war was coming under growing criticism at home.

The army has failed to make a dent in Hezbollah's ability to fire rockets at Israel — the guerrillas fired 170 on Wednesday, for a war total of more than 3,500 — and critics said pushing deeper into Lebanon would not stop such attacks since longer-range rockets can still reach Israel.

Under the army plan, Israeli forces would move to the Litani River, some 20 miles from the Israel-Lebanon border. At the moment, more than 10,000 troops are engaged in house-to-house battles against Hezbollah fighters in a strip less than half that size.