Haftar's critics including Turkey accuse him of trying to seize power from the legitimate government through force and deepening a conflict between factions based in the east and west of the sprawling North African country.
Turkish President Recep Tayyip Erdogan has confirmed his country backs the GNA and provides weapons to it under a "military cooperation agreement".
The missiles were apparently discovered this week when forces loyal to the Government of National Accord (GNA) recaptured the strategic town of Gharyan in a surprise attack, seizing the main supply base for Haftar's offensive.
On Saturday, Erdogan, speaking on the sidelines of the G20 summit in Japan, said he did not have "any information" concerning Haftar's threat against Turkish assets.
Haftar's offensive on Tripoli and the GNA began on April 4 when he said he was moving against the terrorist militias operating in the region.
Haftar and his backers say they are trying to free Tripoli from militias that they accuse of destabilising Libya since the fall of Muammar Gaddafi in a NATO-backed uprising in 2011.
The forces of Libya's Khalifa Hifter said Friday that Turkish vessels and interests are "legitimate targets" in its battle to seize the capital of Tripoli, after it accused Turkey of helping rival militias allied with the United Nations -supported government.
While Hafter controls the eastern and southern portions of Libya, it is not clear how the LNA would enforce the declaration in areas held by the GNA, led by Fayez Al-Sarraj and based in Tripoli.
Anwar Gargash, the U.A.E.'s minister of state for foreign affairs, in May called for an immediate return to the UN-led process.
Al-Mismari said Turkish aircraft "provided air cover" and bombed LNA positions in the fight for Gharyan.
The forces of Libya's Field Marshal Khalifa Haftar said that Turkish vessels and interests are "legitimate targets" in its battle to seize the capital of Tripoli, after it accused Turkey of helping rival militias allied with the UN-supported government.
Hundreds of people have been killed and tens of thousands displaced in the offensive on Tripoli, while diplomatic efforts to revive political talks have foundered.
But Mesmari said the attack was repulsed after a "very violent battle". It has several times attacked Tripoli's functioning airport.
The statement added that the Turkish support to the elements has evolved to a direct interference using military aircrafts to transport mercenaries, as well as ships carrying weapons, armored vehicles and ammunition to support terrorism in Libya.
"Forensic reports showed that wounded in Gharyan hospitals were knifed, shot dead in their heads or rammed by cars", he said.