A senior police official said "Criminal terrorists" on Saturday killed at least 20 civilians in several hamlets in the commune Anchawadj, a few dozen kilometers north of Gao.
A local official blamed the attacks on jihadists put the death toll at 24, saying the killings occurred at Ebak some 35 kilometres (23 miles) north of Gao and neighbouring hamlets.
The official, in Gao the main town in the region, described a "general panic" in the area.
The situation in Anchawadj as "very concerning," and civilians were fleeing the area fearing further violence, he added.
Following Saturday's bloodshed, a mine killed a UN peacekeeper Sunday as he was out on patrol further north, at Kidal, the head of the UN's MINUSMA Mali force El Ghassim Wane tweeted.
A MINUSMA official told AFP on condition of anonymity that the peacekeeper was part of the Guinean contingent.
The north of the country is a largely desert region that is all but devoid of state infrastructure.
"A good part of the Gao region and that of Menaka" are occupied by the jihadists, said an official in Gao. "The state must do something."
While there has been no official confirmation that the attacks were carried out by jihadist groups, fighters affiliated to either Al-Qaeda or the Islamic State group are active in the region.
The region has become increasingly violent and unstable since Tuareg separatist rebels rose up against the government in 2012.
Jihadist fighters took advantage of their rebellion to launch their own offensive, threatening the capital Bamako in the south until a French-led force pushed them back in 2013.
The Tuareg separatists and the government agreed a peace accord in 2015, but it has yet to be applied.
So now Mali's weak, national government faces both separatist and jihadist insurgencies in the north of the country.
For as well as the separatist groups who were part of the stalled 2015 peace deal, Mali's government also has to contend with the jihadist groups.
Some of the rebel groups have also been fighting each other as they battle for influence and territory. Adding to the volatile mix are traffickers and other criminal groups.
Government stability meanwhile has been interrupted by military coups in August 2020 and May 2021.
Following his latest report into the area, UN Secretary General Antonio Guterres last month warned that instability in Mali and Burkina Faso were undermining attempts to stabilise the region.
The security situation in the Gao region had badly deteriorated in recent months, he said.