A statement from the United Nations Integrated Stabilization Mission for Mali (MINUSMA) said the attack took place near Aguelhok in the Kidal region.
Kidal is the former stronghold of separatist rebels in Mali.
However, there are still several active militant groups in the north despite a 2015 peace agreement between the Malian government and Tuareg rebel groups.
The head of mission, Mahamat Saleh Annadif, said the attack against civilians and UN operations was needless. He added that they will arrest those responsible for these terrorist acts.
"We will have to combine all efforts to identify and apprehend those responsible for these terrorist acts," Annadif said.
''The Secretary-General expresses his deep condolences to the families of the victims, as well as the Government and people of Chad. He wishes a speedy recovery to the injured,'' Stephane Dujarric, spokesman for the secretary-general, said in a separate statement.
''The Secretary-General reaffirms that such cowardly acts will not deter the United Nations from its resolve to continue supporting the people and Government of Mali in their pursuit of peace and stability,'' he added.
No group has yet claimed responsibility for the attack. However, similar attacks are usually claimed by militias linked to Al-Qaeda in the Islamic Maghreb (AQIM).
The West African country is beleaguered with several terrorist groups and French, Malian, and UN peacekeepers carry out counter-terrorism operations there.