"We call on the opposing sides to exercise mutual restraint", it said.
The Syrian government, Iran and Egypt condemned the attack, which activists said has killed at least 18 civilians in the Kurdish-held enclave, Afrin, in the first 24 hours.
An AFP photographer saw Turkish tanks lined up at the border waiting to cross into Syrian territory. Turkish-backed rebels and United States forces have been trading fire there, USA defense officials said.
Skinner said a Turkish operation would be a "serious blow" for the US-led coalition in Syria which still depended heavily on the YPG to stabilise the area after the ousting of IS from major towns. Fierce battles raged to the north and west of Afrin against Turkish forces and their Syrian rebel allies, said Birusk Hasaka, the YPG spokesman in Afrin. The YPG is estimated to have between 8,000 and 10,000 fighters in Afrin.
Turkish Prime Minister Binali Yildirim said the strikes on Afrin marked the start of a campaign to "eliminate the PYD and PKK and Daesh elements in Afrin", referring to the Kurdish Democratic Union Party and the Kurdistan Worker's Party respectively, and using an Arabic acronym for the Islamic State group. "This is our source of concern", Turkish President Recep Tayyip Erdogan said at a press conference earlier in January.
The incursion is likely to further stoke tensions between Turkey and the U.S. after the announcement of a US-backed border force in Manbij, northern Syria, last week.
Operation "Olive Branch", in the Afrin region, is Turkey's second major incursion into Syria during the seven-year civil war.
French Foreign Minister Jean-Yves Le Drian says he will call for an emergency meeting at the UN Security Council over the issue.
A British School Is Warning Its Kids Not To Eat Tide Pods
In early 2017, College Humor, a comedic content company, posted a video about eating laundry pods, reported News4jax. Because, the Internet, and likes, apparently.
"This fighting. must stop", Parly told France 3 television, adding that the Turkish offensive could "deter Kurdish forces who are at the side" of the worldwide coalition battling jihadists in Syria.
The Russian Defense Ministry said on Saturday it had pulled its servicemen out of northwest Syria's Afrin City, where Turkey was waging an offensive against Kurdish forces.
In a sign of the risks to Turkey, four rockets fired by the YPG hit the border town of Kilis early Sunday, damaging one building and lightly wounding a woman.
Turkey launched a ground operation across the border into northern Syria on Sunday, in a move likely to raise tensions with the United States. Washington has backed the YPG, viewing it as an effective partner in the fight against ISIS.
Kurds control two large areas in northern Syria. "The first United States military instructors arrived to train Kurdish units in Syria in 2015 since Washington believed Syrian Kurds to be the most reliable ally in the fight against Daesh and protecting American interests in the region".
The PYD/PKK depends on Afrin to connect to the Mediterranean from northwestern Syria.
Tehran "hopes that the operation would be immediately terminated so as to prevent the deepening of the crisis in northern Syria", it said.