Syria's government has said it will accept a halt to "combat operations", after the US and Russia agreed on a plan for the cessation of hostilities to begin this weekend.
Several parties to the conflict, however, were sceptical that any peace deal would actually take effect.
In a statement on Tuesday, President Bashar al-Assad's government said it would coordinate with Russia to decide what other groups - along with the Islamic State of Iraq and the Levant (ISIL) and al-Nusra Front - should be excluded from the plan.
The government stressed the importance of sealing its borders, halting foreign support to armed groups and "preventing these organisations from strengthening their capabilities or changing their positions, in order to avoid what may lead to wrecking this agreement".
The announcement from Damascus came after the US and Russia said on Monday that the International Syria Support Group had agreed to terms for a cessation of hostilities in Syria.
The agreement called on all sides to sign up to the agreement by midday on Friday, February 26 and to stop fighting by midnight.
Hours after the agreement was announced, the Syrian Opposition High Negotiations Committee (HNC) - the major opposition bloc involved in negotiations - said it would accept the terms of the deal.
It added, however, that it does not believe Assad's regime and its allies would do the same.
"Our main concern in the opposition is that both Russia and the regime are not serious about their commitments to the cessation of hostilities," said HNC spokesman Riyad Naasan Agha.
"Excluding ISIL and Nusra can be a ploy by the regime and their allies to keep slaughtering our civilians and trying to finish off the real Syrian opposition."
READ MORE: The official terms terms for the cessation of hostilities
Al Jazeera's diplomatic editor James Bays, reporting from New York, said some critics believed the timing of the deal would allow different sides in the conflict to push for more territory in the lead-up to the truce on Friday.
"Given everything that is happening in Syria, there is not a great deal of optimism about the proposed cessation of hostilities, particularly as many observers fear there will be an increase in the violence - with the warring sides trying to make gains in the days before it is due to start," he said.
Underscoring those concerns, Russian air strikes continued to pound rebel-held areas of Aleppo city on Monday night, as the government's offensive continued in the province.
Elsewhere, fighting took place on Tuesday between Syrian rebels and the Kurdish People's Protection Units in rural areas in the north and west of the province.
Syria's civil war started five years ago when initially peaceful protests against Assad's rule gave way to a war that has killed at least 250,000 people and forced millions from the country.
Source: Al Jazeera and agencies