It comes as a ceasefire deal, agreed upon at peace talks separate to those led by the United Nations, has helped reduce the fighting in Syria.
Since the latest ceasefire deal in Syria came into force at the weekend, fighting in the war-ravaged country has eased.
Russia, Turkey and Iran brokered the agreement during talks in the Kazakhstan capital Astana last week.
It is intended to reduce violence in four designated "de-escalation zones" in the major areas of conflict in Syria.
The Syrian government has agreed to the deal but says it will not accept the oversight of the United Nations or other international forces in the so-called safe zones.
The country's foreign minister, Walid al-Moualem, has indicated the government will only settle for Russian military police already on the ground.
"There will be no presence for international forces under the supervision of the United Nations. The Russian guarantor clarified that there will be a deployment of the military police and observation posts for these areas. What is required by this memorandum is to separate the groups who signed and those who have not signed or will not sign, like the Nusra Front. They should leave these areas to their destiny. I do not know how it will be, but, for certain, if they come towards our forces, they will not be welcomed."
The deal calls for a pause in fighting and air strikes for six months in and around the rebel-held areas, and it bans the use of weapons in the safe-zone areas.
The United Nations hopes the deal can be implemented in full ahead of peace talks in Geneva, which will reconvene next week.
United Nations mediator Staffan de Mistura says he hopes the deal will be observed.
He has released a statement expressing hope it can lead to a significant de-escalation in violence and an environment conducive to intra-Syrian peace talks.
The agreement also calls on all parties to clear the area of factions like the al-Nusra Front, al-Qaeda's former Syrian affiliate.
Mr al-Muallem says rebel groups, too, must help fight those factions.
"According to the memorandum, we will commit. But if a violation takes place by any group, the response will be crucial, and we hope that this memorandum will reach the separation between opposition groups that signed the ceasefire agreement on 30/12/2016 and between Nusra Front and its allied organisations and Daesh."
The United States has expressed concerns over the agreement.
US defence secretary Jim Mattis says the basic details of the deal are still unclear but the United States owes it to the people of Syria to look into it.
"We're going to have to look at it. The devil's always in the details,* right? So, we've got to look at the details and see if we can work them out, see if we think they are going to be effective, can we actually execute them. In other words, there's a lot of decisions to be made, both in planning ... I would say in planning, coordination among a number of nations and, obviously, in execution."
The de-escalation zones cover parts of the Aleppo, Hama, Homs, Deraa and Quneitra provinces.
It also includes the Eastern Ghouta region outside Damascus.
Not included is the Qaboun district of Damascus, which borders the besieged suburb of Barzeh, where Syrian rebel fighters and their families are being evacuated.
Under a deal agreed upon with the Syrian government, hundreds are being evacuated from the area held by rebels to the opposition-controlled province of Idlib.
The Syrian government has described the evacuations as an alternative to the UN-brokered peace talks in Geneva.
The United Nations, however, has likened it to forced displacement.