President Trump called Turkey's President Recep Tayyip Erdogan on Saturday just days after US forces hit Syrian regime military bases near an area where the Turkish government is aiming to transfer thousands of Syrian refugees.
Trump "expressed deep concern over the violence in Idlib, Syria," the White House said.
"Trump – in a phone call with Turkish President Recep Tayyip Erdogan – conveyed the United States' desire to see an end to Russia's support for the Assad government's atrocities and for a political resolution to the Syrian conflict," Deputy White House press secretary said in a statement.
Trump also thanked Erdogan for attempting to prevent a "humanitarian catastrophe" in northwestern Syria's Idlib province, the White House added.
Idlib has been a stronghold of the opposition and anti-government armed groups since the outbreak of the Syrian civil war in 2011.
In September 2018, Turkey and Russia agreed to turn Idlib into a de-escalation zone in which acts of aggression are prohibited, but more than 1,800 civilians have been killed in attacks by the regime since then.
Some 800,000 people have fled since Syrian regime forces backed by Russian air power intensified an assault on Idlib in December.
As part of the 2018 deal Turkey has 12 observation posts in Idlib to prevent a government offensive but four are now thought to be surrounded by Syrian regime forces.
Turkey has threatened to attack Damascus if it doesn't retreat by the end of this month.
Rights groups have said that more than 80,000 people are sleeping in the open air in freezing temperatures after the bombardment of Idlib. According to the International Rescue Committee at least six children have died of the cold.