Later, Arab League deputy chief Ahmed Ben Helli told Al-Arabiya television no response had yet been received.
"The secretary general of the Arab League has not yet received Syria's official response to the document submitted by the ministerial committee" to end the violence, Ben Helli said.
"As far as I know the Syrian delegation will give an official reply tomorrow during the (extraordinary) meeting," which the Arab League is to hold to discuss the violence in Syria, Ben Helli said.
The proposal is aimed at ending more than seven months of bloodletting which, the UN says, has claimed more than 3,000 lives, mostly civilians killed in a government crackdown on dissent.
Arab foreign ministers are due to hold a key meeting in Cairo on Wednesday to discuss the violence, after weekend talks in Doha with their Syrian counterpart Walid Muallem, at which they offered the plan.
Syrian President Bashar al-Assad is under mounting international and Arab pressure to end the violence and implement wide-ranging political reforms to meet the aspirations of protesters who have rallied almost daily since mid-March.
The Arab League proposals call on Assad to pull tanks off the streets and launch a national dialogue with his opponents.
An Arab League diplomat told AFP in Cairo that "there has been agreement on some minor amendments, but the Arab delegation demanded a final response on Tuesday to the Arab proposal."
He said Syria would inform Qatar -- whose foreign minister chaired the Doha talks -- of its response.
Syria's Arab League representative Yusef Ahmed told AFP in Cairo that Damascus would respond to the plan on Tuesday. "We are dealing positively with the last proposal, which was drafted (at Sunday's meeting) in Qatar."
Algerian Foreign Minister Murad Medelci also sounded upbeat.
"We had a good meeting in Doha and we have found some common group with our Syrian friends. I hope this will be confirmed in Cairo," he said on Tuesday.
The pro-regime Syrian daily Al-Watan said that "Muallem provided the Qatari side with ideas adequate to resolve the crisis in Syria... and requested additional time to consult (Tuesday) with his leadership."
Some diplomats in Cairo expressed concerned that the response from Damascus will be tied to conditions to gain time.
"Syria's answer could be 'yes, but', a manoeuvre to buy time," said one diplomat who attended the Doha talks.
Meanwhile, Syrian activists reported that five more people were killed in the protests-wracked country and dozens arrested, including 60 schoolchildren detained for holding an anti-regime rally in their school yard.
Two civilians were killed when pro-regime militiamen opened fire in central Homs and one was shot by security forces in the northwestern province of Idlib, the Syrian Observatory for Human Rights said.
An officer and a soldier were also killed in Idlib by gunmen believed to be army deserters, the watchdog said, adding that an 18-year-old man also died on Tuesday of gunshot wounds from the previous day near Damascus.
Syrian security forces also rounded up dozens of civilians in Daraa -- cradle of the anti-regime protests that erupted March 15, the watchdog said.
Pro- and anti-regime demonstrations also gripped Deir Ezzor on Tuesday, with state television reporting that thousands rallied in support of Assad while activists spoke of a counter-rally in the eastern city.
Meanwhile, Russian Foreign Minister Sergei Lavrov, during a visit to the United Arab Emirates, reiterated Moscow's opposition to any Libya-style military intervention in Syria.
"If it depends on us, I don't think we will allow anything of that sort to be repeated" in Syria, Lavrov said in Abu Dhabi.
UAE Foreign Minister Sheikh Abdullah bin Zayed al-Nahayan echoed him.
"We do not think that there is any party which is willing to internationalise this matter. At least we Arabs don't," he said.
China, along with Russia, vetoed a Western-drafted resolution at the UN Security Council on October 4 that would have threatened Assad's regime with targeted sanctions if it continued its campaign against protesters.
Last week activists urged the international community to impose a Libya-style no-fly zone on Syria.
And the US-based Committee to Protect Journalists (CPJ) has said it fears for several journalists and bloggers in Syria who have vanished, with no response from authorities as to their fate.
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