It was not clear who carried out the attack about 20 kilometres north of the town of Bambara-MaoudÃ© in the Timbuktu region.
Islamist groups linked to Al Qaeda and Islamic State operate in the region and have made much of the West African country ungovernable.
The dead peacekeepers were from Ivory Coast, the countryâ€™s defence ministry said in a statement.
The UN mission in Mali, known as MINUSMA, has over 13 000 troops to contain violence caused by various armed groups in the north and centre of the country.
The mission has recorded about 230 fatalities since then, making it the deadliest of the UNâ€™s more than dozen peacekeeping missions.
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