Turkey committed to protecting its citizens worldwide: VP Oktay
"If our citizens are not released immediately, those responsible will become a legitimate target and the consequences will be severe," Oktay said.
He added that all related institutions continue making efforts to bring back the citizens to Turkey.
Earlier on June 28, Haftar's spokesman Ahmed al-Mismari announced a ban on commercial flights from Libya to Turkey and ordered his forces to attack Turkish ships and interests in the country.
On June 30, the Turkish Embassy in Tripoli on its website advised its citizens to avoid any steps that will jeopardize their security and safety in the regions under control of the illegal militia loyal to Haftar.
Libya has remained beset by turmoil since 2011 when a bloody NATO-backed uprising led to the ouster and death of long-serving President Muammar Gaddafi after more than four decades in power.
Since then, Libya's stark political divisions have yielded two rival seats of power -- one in Tobruk and another in Tripoli -- and a host of heavily armed militia groups.
Meanwhile, Turkey's presidential spokesman slammed early on July 1 the illegal detention of six Turkish citizens by East Libya-based commander Khalifa Haftar forces.
"Detention of 6 Turkish citizens by Haftar's illegal militia in Libya is an act of banditry and piracy. We expect our citizens to be released immediately," İbrahim Kalın wrote on Twitter.
He added that otherwise, Haftar elements will become "legitimate targets".