Gen. Akram Bouhlaiga said that the troops would be backed by a group of Mig-23 jet fighters, as quoted by the media outlet.
Ajdabiya residents reported that some 150 armed pick-up trucks equipped with anti-aircraft guns were moving on the way to Sirte, according to the publication.
According to the media outlet, Libya's UN-backed unity government is against Hiftar's offensive over concerns that his forces may clash not only with jihadists but also with forces loyal to the Tripoli-based General National Congress.
"We ask all military forces to wait for [the government] to appoint a joint command for the Sirte operation. Any infringement of this order will be considered against military law," the unity government's administration said as quoted in the publication.
After Libyan long-standing leader Muammar Gaddafi was overthrown in 2011 by Western-backed rebels, two rival governments were formed in Tobruk and Tripoli.
The instability triggered the rise of numerous Islamic militant and terrorist groups, particularly Daesh, outlawed in Russia, which has been carrying out attacks on Libyan oil and other infrastructure.
In December 2015, Libya’s rival governments (the internationally-recognized Council of Deputies based in Tobruk and the Tripoli-based General National Congress) agreed to create a Government of National Accord and end the political struggle. Fayez Sarraj currently heads Libya's Government of National Accord.