Turkish warplanes struck civilian homes and positions held by a group allied to the Syrian Democratic Forces (SDF) alliance in a village south of Jarablus in northern Syria on Saturday, the group said in a statement.
The Jarablus Military Council group, part of the Kurdish-backed SDF, said the attack on the village of al-Amarna caused civilian casualties and called it "a dangerous escalation that threatens the fate of the region".
There was no immediate comment from Turkish officials.
A Reuters witness saw unidentified warplanes flying over the border region into Syria from Turkey early on Saturday morning, followed by the sound of explosions.
Turkey is backing an operation that got under way this week by Syrian rebel groups to capture Islamic State-held territory in northern Syria at the Turkish border.
The village of al-Amarna is some 10 km (6 miles) south of Jarablus, a town captured from Islamic State by the Turkey-backed rebels this week. An official in one of the Turkey-backed rebel groups said SDF-allied fighters had positions in al-Amarna.
The Jarablus Military Council was set up with the stated aim of capturing the Islamic State-held town. Its statement called the Turkish actions on Saturday provocative. "We confirm our ability to defend ourselves," it said.
It added that its forces had not approached the border strip to avoid any clashes with Turkish forces or the Syrian rebels they support, adding that "if they do not attack our forces, then we will keep the border strip secure".
The Turkish-backed operation aims partly to prevent the Kurdish YPG militia or its allies further expanding their influence in northern Syria. The YPG is a critical component of the SDF.