Russia is counting on foreign supporters of anti-government forces in Syria to ensure that a ceasefire called by the United Nations was observed, the foreign ministry said on Sunday.
Clashes were reported on Sunday between insurgents and government forces in rebel-held areas near Damascus, despite the UN resolution demanding a 30-day nationwide truce.
"We count upon foreign patrons of anti-government militant groups ... to ensure that their charges stop combat activities in the interests of the quickest and safe transit of humanitarian convoys," the ministry said on its website.
"We will watch this closely."
Saturday's Security Council resolution followed seven days of bombing by pro-government forces on besieged rebel-held suburbs of the city.
Iran said earlier that attacks would continue on areas near Damascus "held by the terrorists", the Tasnim news agency quoted its chief of staff as saying.
Several previous ceasefires have unraveled quickly in the seven-year war in Syria, where government forces have gained the upper hand with the help of key allies Iran and Russia.