Attackers dressed as traditional Donzo hunters killed 37 civilians in the village of Koulogon on Tuesday, said the Malian government in a statement.
"The casualty toll includes several wounded and many burned homes," the statement added.
Violence has increased in central Mali between nomadic Fulani herders and Bambara and Dogon farmers, sparked by accusations of Fulani grazing cattle on Dogon land and disputes over access to land and water.
The United Nations recorded more than 500 civilian deaths in the area in 2018.
In June, 24 members of the Fulani community were killed in an attack a UN probe blamed on the Dogon
Several houses were set on fire in Tuesday's attack some 117km from the regional capital, Bankass.
"The attackers were gunmen wearing traditional donzo clothing," and they struck at around 5am local time, the same as GMT, a security source in Mopti told AFP news agency.
Allaye Yattara, a Fulani herder who said he had witnessed the killings, told AFP: "Our village chief Moussa Diallo was killed in the attack along with old women, (and) a girl, all members of his family."
Karim Keita, a legislator and son of Malian President Ibrahim Boubacar Keita, condemned what he termed a "criminal act", and added: "Only the investigation will reveal the reasons" for the killings.
He was in the area after spending New Year's Eve with Malian soldiers in Mopti.
Since the death in November of Fulani figure Amadou Koufa, attacks have increased between the Fulani and ethnic Bambara and Dogon peoples.