The media outlet did not provide additional information on what the offensive is expected to take place.
Damascus-led forces carried out missions in al-Sukhneh, al-Sawaneh and Khneifis in the province of Homs, killing an unspecified number of terrorists and destroying militant infrastructure.
The Russian aircraft "pounded the defense lines of the ISIL terrorist group around Palmyra on Tuesday morning in preparation for a large-scale attack to take back the ancient city," the Fars news agency reported, using an acronym for the organization also known as Daesh.
The ancient city of Palmyra, home to monumental ruins and priceless antiquities, has been on the verge of total destruction since May, when militants, notorious for reducing cultural sites to rubble, captured the strategically important city.
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.