Libya's unity government issued an arrest warrant for General Haftar for allegedly ordering deadly air attacks against civilian areas, Al-Jazeera reported.
Six of Haftar's officers were also named in the warrant, which was issued by the military prosecutor general and published by the unity government's press office.
The United Nations (UN)-affiliated WHO said in a post on Twitter it had deployed medical specialists to support front-line hospitals as the recent fighting had also left more than 900 wounded.
According to WHO, at least 18 civilians were among those killed in the fighting that broke out on April 4 when Haftar launched an offensive to take Tripoli, which is controlled by the UN-recognised Government of National Accord (GNA).
WHO added that it was keeping medical and surgical teams deployed at field hospitals near the front lines as Haftar's Libyan National Army (LNA) remained in the capital's Southern outskirts and battled armed groups loyal to the government.
Meanwhile, on Thursday, armed groups attacked a major airbase in Southern Libya that is controlled by the LNA. The Tamanhint base near Sabha is the main base in Southern Libya, which the LNA seized earlier this year.
Fighting was continuing at the base, Sabha Mayor Hamid Rafaa al-Khiyali and an Eastern military official said, without giving more details.
The identity of the attackers was not immediately clear.
More than 25,000 people have been displaced by the clashes, the International Organization for Migration reported on Wednesday.
During a tour of the Tripoli neighbourhoods worst hit by the rocket fire on Tuesday, GNA head Fayez al-Sarraj said the UN Security Council must hold Haftar to account for his forces' "savagery and barbarism".
"It's the legal and humanitarian responsibility of the Security Council and the international community to hold this criminal responsible for his actions," al-Sarraj stated in footage of the tour released by his office.
He added that his government would seek Haftar's prosecution for war crimes by the ICC in The Hague.
Haftar has concentrated his forces near Tripoli, using mainly the Jufrah airbase but also Tamanhint to fly in material and send it on by road up North towards the Mediterranean coast.
The LNA seized Libya's sprawling South with its two main oilfields earlier this year, although tribesmen with flexible loyalties remain strong in the sparsely populated desert region.
The UN's Libya envoy, Ghassan Salame, warned on Thursday of "a widening conflagration" in the North African country, saying international divisions had encouraged Haftar to launch his assault on Tripoli.
Despite days of heaving fighting, Salame told AFP news agency there was a stalemate South of the capital.
"After the very first successes of the Libyan National Army two weeks ago, we are witnessing a military deadlock," he added.
The resurgence of open conflict in Libya threatens to disrupt oil flows, increase migration across the Mediterranean Sea to Europe, and allow armed groups to exploit the chaos.
Benghazi-based Haftar enjoys the backing of Egypt, the United Arab Emirates and Saudi Arabia, which view him as an anchor to restore stability.