An IS commander and a Danish IS fighter were among those killed, Xinhua reported citing the Syrian Observatory for Human Rights.
The US-led anti-terror coalition has recently focused its strikes against the IS positions in Kobane, also known as Ayn al-Arab, to keep the group from capturing that strategic city on the Syrian-Turkish border.
The Turkish government has also allowed Iraqi Peshmerga forces and Turkey-loyal Syrian rebels to cross into Kobane, Syria's largest Kurdish enclave, via Turkey to join the fight against the IS there.
The Syrian government lashed out at Turkey, accusing it of flagrantly violating Syrian sovereignty by allowing foreign fighters and "terrorists" to cross the borders.
Meanwhile, the observatory, which relies on a network of activists on the ground, said IS fighters in the northern province of al-Raqqa executed as many as 20 Syrian military personnel, most of whom were officers.
It added that the IS had previously captured those officers when its fighters stormed a key military base earlier this year in al-Raqqa, which has now come fully under IS control.
The IS has self-proclaimed an "Islamic caliphate" in areas striding Syria and Iraq. It has also succeeded in capturing almost all of the oilfields in the oil-rich province of Deir al-Zour in eastern Syria on the border with Iraq.