The monitoring mission was suspended in mid-June when its head, General Robert Mood, said fighting posed a threat to his unarmed observers.
Mood returned to Damascus Monday following meetings in Switzerland, where world leaders agreed that a transitional government would help end more than a year of bloodshed.
A U.N. spokesperson said the organization was ready to engage with all the parties concerned.
"We are here, we are eager to resume our work once the parties recommit to the cessation of violence, to a sustained cessation of violence and to the implementation of the six point plan."
On Monday the observers visited local hospitals. Those still in the country have been limited to humanitarian work since the suspension of the full mission.
