The attack took place at about 06:00 in the northern town of Kidal. Residents said at least two suicide bombers were involved and a car bomb was detonated.
A soldier from Chad was killed and at least one other was injured.
A 9,000-strong UN force has been responsible for peacekeeping operations in Mali since July 2013. It regularly comes under attack from militants.
An official from the UN force, known as Minusma, confirmed the attack to Reuters news agency, but did not provide further details.
French and African troops intervened in Mali in January 2013 to stop the southern advance of al-Qaeda-linked fighters on the capital, Bamako.
The insurgents were expelled from the northern towns but have continued attacks against Minusma, which took over responsibility for security in the country from the French.
Gunmen have launched an attack on a UN camp in Mali, killing a UN peacekeeper, residents and eyewitnesses say.