"If the terrorists stop their fire, than the (army) will halt its fire," said Maj. Gen. Benny Gantz, the head of Israel's ground forces.
"The next few days are days of uncertainty," Gantz said.
The truce agreement was to take effect Monday morning, and Israeli troops were to remain in southern Lebanon until they are replaced by the Lebanese army and a U.N. force, he said.
"The (army) will respect the agreement and will defend its forces and its citizens," he said.
Gantz's announcement came as the army reported that Hezbollah fired more than 250 rockets into Israel on Sunday, the worst barrage against northern Israel since the fighting began more than a month ago.
The rockets killed one Israeli during the day.
In other developments:
Israeli warplanes pounded south Beirut with at least 23 missiles, most of them slamming into a Hezbollah stronghold in a two-minute period Sunday within minutes of the Israeli government's approval a U.N. cease-fire plan that was to go into effect 17 hours later.
The missiles slammed into the hard-hit Dahiyeh suburb, a Hezbollah stronghold, where a second salvo of three rockets hit about 90 minutes after the Lebanese Cabinet announced postponing a crucial meeting that was to have taken up implementation of the U.N. cease-fire plan, including the promised dispatch of 15,000 Lebanese soldiers to the south of the country.
The Lebanese force was to eventually be joined by an equal number of U.N. peacekeeping troops to police south Lebanon as Israel withdrew. The Cabinet cancellation was sure to delay the process.
The meeting was believed to have been postponed in a dispute over sections of the cease-fire plan that demanded the disarmament of Hezbollah fighters south of the Litani River that was to be taken over by the Lebanese-U.N. peacekeeping force.
Statements on both sides of the border portend no quick end to the bloody conflict despite the U.N.-demanded cease-fire. The U.N. document calls for Israel to withdraw in conjunction with the insertion of a strengthened U.N. peacekeeping force of about 15,000 troops and an equal number of soldiers from the Lebanese army. That could take days, perhaps weeks.
CBS News foreign affairs analyst Pamela Falk calls the U.N.'s resolution a "diplomatic achievement." However, Falk notes the escalation in violence shows "that the spirit and intent of the U.N. resolution that the Secretary General (Kofi Annan) called for, is not seen on the ground yet."
Falk adds that, "There is little doubt that the agreement on a U.N.-mandated ceasefire and the terms of longer term political solution, put the Security Council in the drivers' seat, at least in terms of being considered a good-faith broker in the region and that also adds to a peacekeeper legacy for the outgoing Secretary General."
The Israeli Cabinet approved the cease-fire resolution by a 24-0 vote, with one abstention.
"In wake of this agreement, Hezbollah won't continue to exist as a state within a state," Prime Minister Ehud Olmert was quoted by army radio as telling his ministers. "The Lebanese government is our address for every problem or violation of the agreement."
A heated debate erupted during the Cabinet session, with minister Ofir Pines-Paz criticizing the government's decision to order an expanded ground offensive in the days before the cease-fire is to take effect.
Former Defense Minister Shaul Mofaz abstained in the vote, said a senior government official who spoke on condition of anonymity because he was not authorized to discuss the details of the meeting with reporters.
Israel made it clear it will maintain its armed presence in south Lebanon until it is replaced by Lebanese army soldiers and a beefed-up United Nations force, as outlined in the resolution.
"When the Lebanese and multinational force enters, Israel will withdraw and not before," said Yaakov Edri, the minister who handles relations with parliament.
Israel has tripled the number of troops to about 30,000, reported CBS News correspondent Allen Pizzey.
After a month of fighting in which more than 100 soldiers died, Edri told reporters, "I don't think it would be correct to say it was an outright victory. But on the other hand, Hezbollah will think twice about attacking Israel next time."
Earlier Sunday, warplanes fired missiles into several gasoline stations in the southern port city of Tyre and killed at least 15 people in those and other attacks as Israeli jets ranged across the skies above Lebanon from north to south.
At least 19 Lebanese were killed in Israeli airstrikes in Lebanon on Saturday, while the Israeli army lost at least 24 soldiers in heavy ground fighting in the thrust northward. Five soldiers were killed after Hezbollah shot down an Israeli helicopter, the Israeli army said.
Hezbollah's al-Manar TV said guerrillas were clashing with an Israeli force trying to retrieve the bodies of those killed when the helicopter downed by an anti-tank missile. Two soldiers died when accidentally crushed by a tank.
Israel claimed it killed more than 50 Hezbollah fighters Saturday. The guerrillas reported three deaths but gave no date.
Al-Manar television said an Israeli bulldozer and two tanks were hit along the Litani early Sunday. The Israeli military had no immediately comment.