President Donald Trump has urged Turkey to deescalate its military action in northern Syria to avoid a possible conflict between U.S. and Turkish forces.
The White House says Trump made his appeal during a telephone call Wednesday with Turkish President Recep Tayyip Erdogan.
WATCH: Trump Urges Erdogan to Limit Military Action in Syria
The call came as Erdogan announced Turkey would extend its military operation against Kurds from the Afrin area to the Syrian town of Manbij — a move that wold bring Turkish forces closer to U.S. forces working with the Kurds.
A White House statement says Trump is concerned that by "escalating violence in Afrin, Syria risks undermining our shared goals in Syria."
They include the lasting defeat of Islamic State and helping Syrian refugees return home while avoiding civilian casualties.
The statement also said Trump expressed concern about "destructive and false rhetoric" coming from Turkey, but did not specify what Trump was talking about.
Erdogan's office said the Turkish president urged Trump to stop supplying U.S. weapons to the Kurdish fighters in northern Syria. Erdogan said its the military operation is aimed at purging "terrorist elements" in northern Syria and protecting Turkish national security.
"We will clean our region from this trouble completely," Erdogan later said. "This operation will continue until the last member of the terror organization is neutralized."
The Kurdish militia that controls Afrin, the People's Defense Units (YPG), has the support of several thousand U.S. special forces in the region.
The Kurds played a large part in driving out Islamic State from most of northeastern Syria.
But Turkey considers the YPG as part of the long Kurdish insurgency for an independent Kurdistan which would include part of Turkey.
Turkey regards Kurdish separatists as terrorists.