According to the so-called Syrian Observatory for Human Rights on Wednesday, Syrian helicopters and fighter jets bombarded the positions of the terrorists in the city, located 215 kilometers (133 miles) northeast of the capital, Damascus, for the second day in a row.
The London-based group added that several ISIS terrorists were killed in the airstrikes.
The observatory also noted that Syrian fighter jets pounded the positions of militants in the town of al-Sekhneh in the eastern countryside of Homs and on the southeastern city of al-Qaryatayn.
Syrian warplanes had conducted similar airstrikes against the militants a day before, killing over three dozen terrorists.
Most residents of Palmyra have fled the city after the Daesh invasion and Syrian forces have since been fighting against the terrorists to regain control of the ancient city.
The ISIS militant group, which controls swathes of land in Syria and Iraq, overran the historic city in the central Homs Province on May 21.
The city of Palmyra has been listed as a world heritage site by the United Nations Educational, Scientific and Cultural Organization (UNESCO) since 1980.
ISIS Takfiri terrorists have ransacked and demolished several ancient sites, shrines, and manuscripts as well as mosques in Syria and Iraq.
Gruesome violence and the destruction of priceless artifacts have become hallmarks of the Takfiri group; Press TV reported.