The Britain-based Syrian Observatory for Human Rights said the air strikes hit Islamic State positions in the northern outskirts of Raqqa city, a major stronghold of the hardline Islamist militants.
The areas hit by the strikes included the 17th Division, a Syrian army base that Islamic State seized in July, the Observatory said.
The U.S.-led coalition began bombing Islamic State in Syria in September. Syria’s nearly four-year-old civil war has continued unabated throughout the country.
The Observatory said 19 people were killed including seven women and two children when Syrian government warplanes struck the town of Jassim in the southern province of Deraa on Sunday.
Dozens of others were wounded and the death toll was expected to rise because a number were in critical condition, the Observatory said.
Fighting also continued in the Kurdish town of Kobani, northwest of Raqqa on the border with Turkey, where Kurdish defenders have been holding off an assault by Islamic State fighters for more than two months.
At least 62 people have been killed in fighting in Kobani, known as Ayn al-Arab in Arabic, since early on Saturday, the Observatory said.