UN spokesman Farhan Haq said the helicopter was monitoring clashes on the ground when it crashed near Tabankort.
The UN mission in Mali, MINUSMA, has dispatched a team to the site to verify possible casualties and the circumstances of the incident, said Haq.
"We can confirm that an attack helicopter of the UN mission in Mali, MINUSMA, with a crew of two personnel crashed earlier this morning south of Tabankort, in Gao region," said Haq.
UN diplomats separately confirmed that the attack helicopter and the crew had been supplied by Germany to MINUSMA.
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A UN official in Gao earlier said the crash was apparently an accident.
Northern Mali is the site of frequent fighting between armed groups, as well as a haven for jihadist activity.
In 2012, Mali's north fell under the control of jihadist groups linked to Al-Qaeda who exploited an ethnic Tuareg-led rebel uprising.
While the Islamists were largely ousted by a French-led military operation, attacks have continued on civilians, the Malian army as well as on UN and French forces.