Turkey on Sunday warned forces of military commander Khalifa Haftar would become "legitimate targets" if attacks on Ankara's missions and "interests" continue.
The Turkish government under President Recep Tayyip Erdogan has stepped up its support in recent months for Libya's UN-recognised Government of National Accord (GNA) in Tripoli after Haftar launched an offensive last year to seize the capital.
"We stress that if our missions and interests are targeted in Libya, Haftar's forces will be considered legitimate targets," the Turkish foreign ministry said in a statement.
"The attacks on diplomatic missions including our Tripoli embassy, Mitiga airport, civilian planes preparing to take off and other civilian infrastructure, and those which kill civilians or injure them, constitute a war crime," it added.
The ministry said the international community had a "collective responsibility" to stop "putschist Haftar", as it reiterated its support for the GNA.
Libya has been mired in chaos since the ouster and killing of long-time dictator Moamer Kadhafi in 2011, with rival administrations in the east and west vying for power.
Haftar controls swathes of eastern Libya and is backed by countries with whom Turkey's relations are strained including the United Arab Emirates.
After signing a military agreement late last year, Turkey dispatched troops and pro-Turkish Syrian fighters to support the GNA.
Erdogan on Monday appeared to indicate that Turkey believed the situation would improve in the GNA's favour with Haftar losing more ground, saying: "We will, God willing, get new good news from Libya, soon" but he did not give further information.