"The opposition welcomes the army's decision and will proceed with the withdrawal of all its armed elements so that control of the capital is handed over to the military," an opposition statement said.
The announcement came shortly after the army said it was overturning a government decision to reassign the head of Beirut airport security and to probe a communications network set up by Hezbollah.
But MP Ali Hassan Khalil of Hezbollah's Shiite ally Amal said the opposition would maintain a civil disobedience campaign against the Western-backed government after Prime Minister Fuad Siniora urged the army to intervene.
Amal militants were among the first to pull back from the streets of west Beirut after four days of bitter clashes that left at least 34 people dead nationwide and brought the country dangerously close to a new civil war.
The White House welcomed Saturday's lessening of violence in Lebanon but warned that "our concerns regarding Hezbollah are unchanged."
"They continue to be a destabilising force there with the backing of their supporters, Iran and Syria," US National Security Council spokesman Gordon Johndroe said.
The takeover of west Beirut was a dramatic display of Hezbollah's military might and capacity to impose its will.
The army urged all armed militants off the streets in a bid to end the violence which also forced the closure of Lebanon's only civilian airport and Beirut port.
"The army command calls on all parties to (help restore calm) by ending armed protests and withdrawing gunmen from the streets and opening the roads," a statement said.
It said that the airport security chief would remain in his post pending an investigation and that it would examine the Hezbollah's communications network.
"Brigadier General Wafiq Shqeir will remain in his post until appropriate procedural measures have been taken after a probe," the statement said.
"As for the telecommunications network, the army will look into the issue in a manner that is not harmful to the public interest or the security of the resistance" against Israel, it added.
The military said it had acted after Siniora made a televised address to the nation in which he accused Hezbollah of staging an armed coup but also urged the army to restore order.
The violence pitted mainly Sunni supporters of the Western-backed ruling bloc against Shiite militants from the opposition, supported by Iran and Syria.
In his first public reaction to Hezbollah's takeover of west Beirut, Siniora decried what he called a "poisonous sting" to democracy.
He said Hezbollah's weapons could no longer be considered to be legitimately held because they had been turned on the Lebanese themselves.
Sixteen people were killed in Saturday's violence, two of them at a funeral procession for an earlier victim of the sectarian fighting.
Hezbollah also said it blamed Druze leader Walid Jumblatt for the death of at least two of its members in Aley, east of Beirut.
Jumblatt admitted there had been "an unfortunate incident" in the predominantly Druze and Christian town, saying: "Three people were killed. Two bodies were found and turned over to the army."
He did not expressly admit his supporters were responsible, but said if unconfirmed reports that the victims had been tortured proved true he would "personally take responsibility for it."
Fourteen people were also killed in north Lebanon in clashes between rival supporters, a security official told AFP.
An uneasy calm had settled over most of west Beirut earlier as people ventured out in the affected areas and cleaning crews swept away the debris.
The main road to the airport remained blocked for a fourth straight day and there were no incoming or outgoing flights.
Foreigners continued to leave Lebanon by road to Syria, with Turkey and Kuwait evacuating their citizens.
The unrest led to urgent international appeals for calm and Arab foreign ministers were due to hold an emergency meeting on the crisis on Sunday, amid fears among Sunni governments of an increase in the influence in Lebanon of Shiite Iran.
Washington on Friday pointed the finger at Iran and Syria for the violence, saying they must be held to account.
"The United States is consulting with other governments in the region and with the UN Security Council about measures that must be taken to hold those responsible for the violence in Beirut accountable," the White House said.
Lebanon's long-running political standoff, which first erupted in November 2006 when six pro-Syrian ministers quit the cabinet, has left it without a president since November, when Damascus protege Emile Lahoud's term ended.
The crippling political divide is widely seen as an extension of the confrontation pitting the United States and its Arab allies against Syria and Iran.
