US-led air strikes hit jihadist positions in the north and east of Syria, including an oil field, the Syrian Observatory for Human Rights said on Saturday.
The raids against the Islamic State group came as the jihadists shelled a camp for people displaced from the flashpoint Syrian town of Kobane, killing two civilians, said the monitoring group.
"Four explosions were heard during the night in Deir Ezzor province (eastern Syria), caused by US-Arab air strikes in the area of the Tanak oil field and an IS checkpoint... killing two people," said the Observatory.
The Britain-based monitoring group, which relies on a network of sources on the ground for its reports, said it was unclear whether the casualties were jihadists or civilians.
IS controls most oil fields in Deir Ezzor province, which borders Iraq.
The US-led coalition, which launched strikes against jihadist positions in Syria in September, also hit IS militants in Kobane.
Known as Ain al-Arab in Arabic, the town on the border with Turkey has been besieged by IS for nearly two months.
Syrian Kurdish forces backed by rebels and Iraqi peshmerga fighters have been battling to expel IS from the town, most of whose residents have fled.
IS shelling on Saturday killed two civilians and wounded four others, including a child, at a camp for people forced by violence from Kobane to the west of the town, said the Observatory.
Separately, the monitor said fighting on Thursday night in a majority Druze region near Lebanon killed 31 combatants loyal to Syria's President Bashar al-Assad and 14 rebels, including Al-Qaeda militants, in an updated toll.
There has been frequent violence in Syria's Mount Hermon, but the toll over recent days has been unprecedented.
A Lebanese security source told AFP that 11 rebel fighters wounded in the latest clashes had been prevented by Lebanese soldiers from crossing the mountainous border area to seek medical treatment.
Later, the Lebanese army allowed a medical team to travel to the border area in order to treat the wounded there.
In recent weeks, Lebanon has all but closed the border officially to incoming Syrian refugees, with troops bolstering border security.
More than 1.1 million Syrian refugees are living in Lebanon, straining the country's limited resources and infrastructure.