Hezbollah and its allies last week routed government supporters and briefly seized control of large parts of Beirut, before handing them over to the army.
The Lebanese army continued to patrol throughout the country on Wednesday with orders to use force to restore security if necessary, security officials said.
Rula Amin, Al Jazeera's correspondent in Beirut, reported earlier that opposition bulldozers had partially opened the road to the airport to allow the delegation through.
"There is some optimism that their visit will bring a literal end to this crisis," she said.
"A deal had been finalised and what we are waiting for now is for the government to meet today and revoke their decisions and when they do that the opposition is going to fully open the road to the airport."
The Arab League delegation will be led by Sheikh Hamad bin Jassim bin Jabr Al-Thani, the Qatari foreign minister, and Amr Moussa, the secretary-general of the Arab League.
Top of the agenda will be efforts to end anti-government protests by Hezbollah supporters and their allies that has led to the shutdown of a number of major roads in Lebanon, including the highway to the airport.
No commercial flights have been scheduled from the country's only international airport for the seventh straight day, an airport official said.
Sources said that if the delegation succeeds in easing tensions, the rival leaders will be invited to Qatar for talks aimed at resolving Lebanon's protracted political conflict.
But Alastair Crooke, director of the Conflicts Fourm think tank, told Al Jazeera there were reasons to be sceptical of how much the Arab League delegation could accomplish.
"I don't think we should expect too much from the Arab League. They were very divided in their meeting in Cairo when they decided to send a delegation," he told Al Jazeera.
"And there are deep divisions over who to hold responsible."
A decision by the government to ban Hezbollah's private communications network and a move to fire Beirut airport's security chief, who is close to the group, sparked the violence last week, the worst in Lebanon since the 1975-90 civil war.
Six days of fighting left at least 65 people dead and around 200 people wounded.
Opposition fighters pulled back after the army reversed the government decisions.
Senior US security officials said Washington plans to intensify its pressure on Syria and Iran over their alleged support for Hezbollah's moves against the Lebanese government.
George Bush, the US president, who arrived in Israel on Wednesday, warned Iran and Syria on the eve of his trip that world powers would not allow Lebanon to fall under foreign domination and vowed to shore up the Lebanese military.
Washington also said it was expecting the UN Security Council to take action next week over the unrest.