It urged "all parties to exercise restraint and avoid causing collateral damage to hospitals, ambulances and health workers."
At least eight ambulances have been hit during clashes on the southern outskirts of the Libyan capital, Presstv Reported.
Libya has been divided between two rival governments, the House of Representatives, based in the eastern city of Tobruk, and the internationally-recognized government of Fayez al-Serraj, or the Tripoli-based Government of National Accord (GNA).
General Khalifa Haftar is presumably loyal to the one in the east.
His self-styled Libyan National Army (LNA) started its offensive against the GNA on April 4.
Meanwhile, the United Nations Office for the Coordination of Humanitarian Affairs said more than 18,000 people fearing violence and clashes have been forced to flee to other safer locations in the past days.
The United Nations refugee agency (UNHCR) warned that the country is in "critical need of assistance."
"The situation on the ground continues deteriorating and number of casualties soaring," UNHCR tweeted.