The so-called Syrian Observatory for Human Rights said it was one of the most sustained government bombardments of Palmyra.
The air strikes killed 12 Islamic State in Iraq and the Levant (ISIL) militants, the British-based group said, Reuters reported.
On Thursday, Syrian jets had carried out at least 12 air strikes on Raqqa, ISIL's de facto capital in the north.
A source told Reuters this week that Syrian forces had started using new types of “very accurate” air and ground weapons allegedly supplied by its ally Russia.
The US has expressed concern over allegations of heightened military involvement by Russia in Syria, with American media saying Russia had deployed troops and heavy weapons to an air base in Latakia, Syria.
Moscows denies the reports, but says it has never kept secret its military cooperation with Syria which is part of efforts to help the Arab state defeat foreign-backed terrorists in heavy battles.
Washington rejects the idea, advocated by Moscow, of cooperating with Syrian President Bashar al-Assad to fight Islamic State in Iraq and the Levant, and has warned Syria not to interfere in its air campaign.
However, the White House did open the door on Thursday to possible tactical discussions with Moscow, and the Pentagon said such talks might be necessary to avoid “miscalculation”.
On Friday, US Secretary of State John Kerry said President Barack Obama saw military talks with Russia on Syria as an important next step and hoped they would take place soon.
“Our focus remains on destroying ISIL and also on a political settlement with respect to Syria, which we believe cannot be achieved with the long-term presence of Assad,” he told reporters. “We’re looking for ways in which to find a common ground.”