Last month, Turkey launched its military incursion into northeast Syria to drive Kurdish YPG fighters from the border and establish a "safe zone".
YPG was the lead force in the Syrian Democratic Forces (SDF), Washington's main ally in the battle against ISIL in Syria.
Erdogan, who links the Kurdish guerrillas to separatists at home, launched the invasion last month after a phone call with Trump, who pulled out U.S. troops who had effectively served as a buffer.
Russian Federation mediated a cease-fire whereby Syrian government forces deployed along parts of the border but also left Turkey in control of a stretch of land inside Syria.
However, officials on Wednesday said the visit would go ahead and that the two leaders had exchanged views on bilateral issues and regional developments during their phone call.
The Observatory said regime forces withdrew from several areas including Um Shaifa, leaving Kurdish fighters alone to face the attacks, which also involved Turkish drones. It said they were killed and wounded north of the town of Tal Tamr, adding that the rangers and the Kurdish Red Crescent had evacuated some of the Syrian troops. The ministry said on its Twitter account that the Syrian Kurdish fighters attacked with mortars, rockets and sniper fire, without saying where the attacks had occurred.
An Associated Press journalist saw four Turkish armored personnel carriers cross into Syria to join the Russian forces.
The Turkish Defense ministry said Friday's joint patrol from the Syrian city of Qamishli city to the town of Derik "has been completed as planned with due care and attention to the safety of our personnel and the public against the provocateurs".
"I will examine this and talk to my colleagues", Erdogan quoted Trump as saying to him, when the Turkish president explained that under previous administrations the commissions in the U.S. Congress had declined such resolutions, but this time the commission had been bypassed. US support for the YPG, which was a main ally in the fight against Islamic State, has infuriated Turkey.
When asked about Trump's comment - in response to accusations of betrayal - that the Kurds had not fought alongside Allied forces on the beaches of Normandy in 1944 against Nazi Germany, Ahmed said Turkey had not been on the side of the Americans in World War Two.
"To come from tens of thousands of miles away and to say, 'We will put the country's wealth, oil reserves to use, ' is against worldwide law".