US President Donald Trump and Turkish leader Recep Tayyip Erdogan on Thursday agreed on the need to de-escalate tension in Syria.
"The leaders agreed on the need for de-escalation in Idlib, Syria, in order to protect civilians," the White House said.
At least nine people were killed on Wednesday when the Syrian army launched missiles that struck a shelter for displaced families in the country's north-west, residents said.
Five children were among those killed in the strike on a disused school in the town of Sarmin in Idlib province and more than 16 people were injured.
The school building was being used by families fleeing a bombing campaign in Idlib, the last opposition bastion in the north-west.
The campaign that started in April had already forced at least 500,000 people to leave for areas closer to the border with Turkey, which jets rarely hit.
Rescue services and witnesses say the bombing has killed several thousand civilians.
Mr Trump spoke out last week against the "carnage" in Idlib.
Damascus denies claims of indiscriminate bombing of civilians, saying it is fighting militants.
Syria's civil war has killed more than 370,000 people since it started in 2011 with the brutal repression of anti-government protests.
In total, 11,215 people, including more than 1,000 children, were killed in the war last year, although it was the least deadly year since the start of the conflict.