Mali's deteriorating security situation is of growing concern as Al-Qaeda-linked groups mount increasingly deadly attacks on domestic and foreign forces.
"Terrorists on motorbikes opened fire" on two soldiers from the National Guard at Gossi, south of Gao, a major city in the region, a military source told AFP.
Another source said the two men were shot in the head.
On Sunday evening, suspected militants also attacked a police station at Hombori, about 90 kilometres (55 miles) south of Gossi.
"The army responded. To the best of our knowledge, there are no victims," a security source told AFP.
At least four civilians were killed in the north on Friday and Saturday and authorities have banned motorbikes and pick-up trucks in some areas to prevent further militant attacks.
Such vehicles are often used by fighters, in the north and the centre of the country.
The ban applies to a dozen "circles" in the central regions of Segou and Mopti and northwest Timbuktu region, a military statement said.
extremists linked to Al-Qaeda took control of the desert north of Mali in early 2012, but were largely driven out in a French-led military operation launched in January 2013.
In June 2015, Mali's government signed a peace agreement with coalitions of non-militant armed groups. But militant insurgents remain active, and large tracts of the country are lawless.