United Nations Support Mission in Libya (UNSMIL) on Thursday condemned Haftar's so-called Libyan National Army (LNA) for "indiscriminate bombardment of the capital Tripoli with rockets, many of which had landed on civilian neighborhoods, resulting in casualties".
In Tripoli, heavy bombardment could be heard into the evening on Wednesday. Following an attack last Monday, water supply was cut to more than two million people in Tripoli and nearby towns.
Now fierce battles are raging to the west of the Libyan capital.
Since mid-2014, Libya has been mired in civil war, pitting the UN-recognized Government of National Accord (GNA) in Tripoli against a rival administration in Tobruk, which is allied with General Haftar.
General Haftar led a deadly offensive to capture Tripoli in April last year, but his forces have been bogged down outside the city. The UN says hundreds have been killed and over 200,000 displaced since Haftar launched his battle for Tripoli.