“The Syrian tragedy will be seen by history as a disgrace for the international community if we do not end it quickly,” Hollande told the General Assembly.
The French leader described Aleppo, which has once again come under a barrage of air strikes, as a “martyred city” and blamed the Syrian regime for the collapse of a US-Russian ceasefire.
“Thousands of children have died in bombings, whole populations are starving, humanitarian convoys are being attacked, chemical weapons are being used.”
“I have one thing to say here: enough is enough,” he said.
The war in Syria, now in its sixth year with over 300,000 dead, is dominating this week’s gathering of world leaders at the United Nations.
US President Barack Obama earlier took the podium to declare that diplomacy was the only way to end the devastating war.
The United States and Russia, the regime’s ally in the war, earlier chaired a brief meeting of the 23-nation group backing the Syrian peace process, but there was no breakthrough.
On Wednesday, the UN Security Council is to meet to discuss the Syria crisis, with distrust between Washington and Moscow running high.
Addressing Russia and Iran, President Bashar al-Assad’s backers, Hollande said they must compel the regime to make peace, warning that “if not, they will also, alongside the regime, bear the responsibility for the division and chaos in Syria.”