Speaking at his weekly audience on Wednesday he told those gathered: "I want to emphasise and reiterate my solidarity with all victims of inhuman conflict in Syria."
"It is with a sense of urgency that I renew my appeal, begging, with all my strength, those responsible, that steps be taken toward an immediate ceasefire, one imposed and respected at least for the time necessary to allow the evacuation of civilians, especially children, who are still trapped under cruel bombardment."
He was speaking as Russian-led airstrikes have resumed in the war-torn country Syria.
Meanwhile Moscow has denounced Boris Johnson and accused the UK of trying to whip up "hysteria" after the Foreign Secretary accused Russia of being involved in bombing an aid convoy in Syria and urged protests outside the country's embassy.
Russian defence ministry spokesperson said Mr Johnson's accusations were "a storm in a glass of muddy London water" and insisted none of his country's aircraft were in the area at the time of the attack.
The comments come after an aid convoy delivering food to a rebel-held area near Aleppo was targeted in an airstrike.
Millions of people have been displaced as a result of the conflict between government-forces and rebel groups.
