Military intervention is “not a solution that can lead to results,” SDF spokesperson Kino Gabriel told Reuters News Agency on Thursday.
“Any military solution, as far as the SDF is concerned, will lead to more losses and destruction and difficulties for the Syrian people,” Kino said.
Earlier on Thursday, Assad warned in an interview with the broadcaster Russia Today that he would not hesitate to use force to reclaim the one-third of the country under SDF control, if negotiations fail.
He also warned that the US should learn the lesson of Iraq and remove its troops from Syria.
“The only problem left in Syria is the SDF,” Assad said.
“We’re going to deal with it by two options,” he said.
“The first one: we started now opening doors for negotiations. Because the majority of them are Syrians, supposedly, they like their country, they don’t like to be puppets to any foreigners,” Assad said in English.
“We have one option, to live with each other as Syrians. If not, we’re going to resort … to liberating those areas by force.”
Founded in 2015, the SDF says it is fighting to establish a democratic and federal Syria along the lines of the Rojava region in the north.
Its makeup largely consists of Kurdish YPG fighters and smaller groups of Arab, Turkmen and Armenian fighters.
Last year, the US began arming them before an offensive to recapture Raqqa, the former de facto capital of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).
The Kurdish YPG and its allies have carved out autonomous regions in the north, and they now control nearly a quarter of Syria.
Both the SDF and Russian-backed Syrian government troops are engaged in separate operations against ISIL in eastern Syria.
Assad said a confrontation between Russia and US forces over Syria had been narrowly avoided “by the wisdom of the Russian leadership”.