The Sunday airstrike missions are believed to be part of the final phase before the town will be liberated.
"The ground forces, including the Syrian Army, popular forces and Hezbollah fighters are waiting for the OK of the headquarter of the operation to launch their large-scale attack on the ISIL strongholds," the media outlet quoted anonymous sources on the ground as saying.
The Temple of Bel, the Baalshamin temple and the Arch of Triumph are among the priceless pieces of ancient art which have already been lost. The temples were destroyed in August and the gateway built by the Romans was blown up in October.
Daesh has also used the site for mass executions.
The sources did not say when the operation to free Palmyra will take place but in recent days the Syrian Army has been making gains in neighboring areas, killing dozens of militants, as well as destroying their infrastructure and weapons.
Damascus-led forces have carried out their latest operations near al-Bayarat, al-Madina and al-Tamthylia.