The UN secretary-general also demanded that a Security Council resolution for a 30-day ceasefire in Syria be "immediately implemented and sustained."
The UN chief stressed that "Security Council resolutions are only meaningful if they are effectively implemented, and that is why I expect the resolution to be immediately implemented and sustained."
UN members approved a ceasefire in Syria on Saturday after weeks of wrangling over the issue. UN Secretary-General Antonio Guterres had earlier called the conflict "Hell on Earth".
The resolution was stuck after Russia demanded that the rebel group fighting President Bashar al-Assad's forces also comply with the resolution. After protracted talks, the resolution was finally passed unanimously ensuring a 30-day ceasefire in the war-torn country.
The Syrian military forces have not commented on the resolution so far.
In November, Russia had used its veto to end a UN-backed investigation of chemical weapons in Syria.
In May last year, Russia, Iran and Turkey had signed an agreement to set up de-escalation zones, in order to prevent airstrike-related incidents in some parts of Syria.