The United States has called on Turkey to halt military strikes on the Syrian Kurdish Democratic Union Party (PYD) and the Syrian Army in the northern province of Aleppo.
"We are concerned about the situation north of Aleppo and are working to de-escalate tensions on all sides," State Department spokesman John Kirby said in a statement on Saturday.
Turkish media outlets, quoting military sources, reported that the Turkish Army shelled PYD targets near the town of Azaz, and also targeted Syrian Army positions.
"We have urged Syrian Kurdish and other forces affiliated with the YPG not to take advantage of a confused situation by seizing new territory," Kirby said.
"We have also seen reports of artillery fire from the Turkish side of the border and urged Turkey to cease such fires," he added.
Kirby said Turkey and the Syrian Kurdish fighters must work together as they both share the serious threat of Daesh in northern Syria.
He had earlier said that Washington does not consider the Syrian Kurds as terrorists. The comment prompted Turkey to summon the US ambassador in Ankara.
Turkish President Recep Tayyip Erdogan also warned the US that it has to choose between Ankara and the Syrian Kurds.
The US and some regional players, including Saudi Arabia and Turkey, have been financing and arming various militant groups, including Daesh and al-Qaeda, in Syria.
The foreign-sponsored conflict, which flared up in March 2011, has reportedly killed some 470,000 people and displaced nearly half of the population, according to the Syrian Center for Policy Research.