French President Francois Hollande has described the suspension of Syrian peace talks as "very worrying".
Mr Hollande, who spoke during a visit to Syria's neighbour and Western ally Jordan, said the decision by a Syrian opposition delegation to halt talks in Switzerland could quickly lead to renewed fighting, more air strikes and suffering among civilians.
A complete collapse of the talks would mean "no hope," he said during a meeting with Jordan's King Abdullah II and underscored the need for a political solution to the conflict.
Jordan has been significantly affected by the fighting, which is now in its sixth year. The Syria conflict helped to give rise to Islamic State extremists, who control large areas of Syria and Iraq, which also borders Jordan.
"I know what you are facing in this area," Mr Hollande told Jordan's king. "The threat is not a virtual one, it's a real threat at your borders. We are co-operating at the military level, and our co-operation is really exceptional."
Mr Hollande was also visiting an air base in Jordan from which French aircraft have staged air strikes against IS. Jordan is also a member of the US-led military coalition against the extremists.
The kingdom, meanwhile, has absorbed more than 630,000 Syrian refugees, out of a total of close to 5 million Syrians who have fled their homeland since 2011.
Since last year, Jordan has further tightened restrictions on the entry of refugees, causing thousands to be stranded in a remote border area in the desert. Jordan's government said earlier this week that the number of Syrians waiting to be let in has reached 50,000.
Jordan has argued that its security comes first and that it can only permit Syrians to enter after careful security vetting. Human rights groups have warned that refugees endure tough conditions and have urged Jordan to carry out the vetting at better facilities in the country.
Mr Hollande said Jordan has "shown great solidarity, and there are still refugees coming from Syria fleeing the fighting around Raqqa or around Palmyra".
"You need to give them the support they need, but at the same time make sure that there are no terrorists infiltrating among the refugees," Mr Hollande added.
As for the Geneva talks, Mr Hollande said it was "very worrying to see that the negotiations have been suspended".
In Geneva, the Syrian opposition delegation said there can be no solution in Syria with President Bashar Assad in power, and called for international monitors to observe a ceasefire that has all but collapsed.