Another two civilians, including a child, were killed and 20 others wounded in regime attacks carried out in East Ghouta neighbourhood of Damascus.
At least three civilians were killed and six others injured in a PYD attack on Sunday in Syria's northern Aleppo province, a pro-opposition Syrian civil defence official said.
The fatalities occurred when the PYD/YPG militants attacked the opposition-held Marea town, Alaa Nima, a White Helmets official said.
He said a pregnant woman was among the victims and that three children were also injured in the attack.
The PYD is the main partner for the US-led SDF coalition against Daesh in Syria. Turkey has been concerned about the US decision to arm the YPG/PYD.
The YPG is the military wing of the PYD, a Syrian affiliate of the PKK, which Turkey, the US and EU consider a terrorist organisation.
Earlier last month, the head of US special forces Army General Raymond Thomas said that rebranding the YPG/PYD to SDF was done to give the group a voice in Syria talks and to assuage Ankara.
The PKK has waged an armed campaign against Turkey for more than 30 years that has led to the deaths of more than 40,000 people.
"PYD has been targeting the town for a long time with a variety of weapons," Nima said, stating that Sunday's attack targeted residential areas.
A number of opposition fighters were transferred to Turkey for treatment after critical injuries in clashes with the terrorist group in the western part of Marea, Hussein said.
PYD captured Syrian city of Tal Rifaat as a launching point of their attack against the opposition-held areas of Marea and Azaz in Aleppo province.
Syrian regime continues to target civilians
At least two civilians including a child were killed in regime attacks in East Ghouta neighbourhood of the capital Damascus, an official said on Saturday.
Mahmoud Atham, an official from volunteer rescue group White Helmets, said the Assad forces targeted Ein Tarma suburb of East Ghouta with 16 air strikes and 70 missiles.
Atham said 20 others – including 5 women and 8 children – were wounded in the attacks.
Eastern Ghouta is one of de-escalation zones announced by Turkey, Russia and Iran in Kazakh capital of Astana in May.
Since the civil war in Syria erupted in March 2011, more than 400,000 people have been killed and million others have been left dicplaced, according to the UN.