President Donald Trump called for a "rapid de-escalation" of the Libyan conflict on a call with Turkish counterpart Tayyip Erdogan on Saturday, the White House said, after recent gains by forces backed by Turkey prompted threats of retaliation.

Ankara said the NATO allies agreed to continue pursuing stability in the eastern Mediterranean region, including in Syria, while a spokesman for Erdogan said the international community must stand with Turkey in the Libyan conflict.

Turkey backs Libya's internationally recognized Government of National Accord (GNA), which has made significant military gains in recent weeks in battles with the eastern-based Libyan National Army (LNA) of Khalifa Haftar.

With Turkish help, the GNA has seized a string of towns, captured a strategic airbase and destroyed several of the LNA's Russian-made air defense systems.

The surge has put pressure Haftar's 13-month campaign to seize the capital Tripoli and has squeezed his foreign backers Russia, Egypt and the United Arab Emirates.

White House spokesman Judd Deere said in a statement: "President Trump reiterated concern over worsening foreign interference in Libya and the need for rapid de-escalation."

As the LNA has promised to respond with a massive air campaign, diplomats have warned of the risk of a new round of escalation with the warring sides' external backers pouring in new weaponry.

Turkey "will not bow to threats by Haftar or anyone else," Turkey's presidential spokesman Ibrahim Kalin said separately in an interview on NTV.

"The international community must take a stand against Hafter. We need to go back to the table for a political solution as soon as possible," Kalin said.