The Syrian conflict needs to be resolved through negotiations involving government and opposition forces, Russia and the United Nations, Italian Prime Minister Paolo Gentiloni said.

Italy's foreign minister earlier gave his backing to a U.S. air strike against a Syrian airfield on Friday, saying it was a suitable response to Syrian aggression and a deterrent against the use of chemical weapons by its leader Bashar al-Assad.

Gentiloni, whose country holds the rotating presidency of the Group of Seven industrialised nations, told reporters the "limited" strike should not be seen as a stage in a process of military escalation.

The conflict in Syria must be resolved by "negotiation that includes the forces of the regime and the opposition, overseen by the U.N., with a decisive and construcive role for Russia," Gentiloni said.

He added that he had recently spoken to the leaders of France and Germany and this position was shared by both of them.