Five raids killed at least 16 militants and injured dozens more when bombs hit militant-held areas in the town of Muhassan just over 100 km (60 miles) from Iraq.
Syrian fighter jets were seen taking off from the Deir al-Zour military airport to bomb several areas under the control of ISIL and witnesses and activists said areas near the border with Iraq close to the city of Abu Kamal were bombed.
ISIL's seizure of large amounts of weaponry and money from looted banks in Iraq after its capture of the city of Mosul have emboldened followers in Syria and instilled fear among tribal leaders in the eastern region, some residents say.
The group's headquarters were the target of intensive raids by Syrian air forces last week.
ISIL's toughest militants said to be behind gruesome executions that showed the real face of the group to the world, including Chechen Abu Omar al-Shishani, believed to have a crack force of over 800 terrorists.
British defense study center IHS Jane's estimated that some 10,000 militants are fighting for groups affiliated with al-Qaeda such as al-Nusra Front, and the rest fight for different militant groups.
Syria has been gripped by deadly unrest since 2011. According to reports, Western powers and their regional allies - especially Qatar, Saudi Arabia, and Turkey - are supporting the militants operating inside the country.
NTJ/HH