The epicenter of the quake was located about 19 kilometers (12 miles) northwest of the city of Port-de-Paix, the US Geological Survey reported.
Government spokesman Eddy Jackson Alexis told AFP that 11 people were so far reported dead, seven of them in Port-de-Paix, the capital of Haiti's Nord-Ouest department.
Four others were killed in the town of Gros-Morne, about 50 kilometers to the southeast.
The quake, which was felt across the country, struck at 8:10 pm (0010 GMT Sunday) at a shallow depth of 11.7 kilometers.
Haiti's civil protection agency said two minor aftershocks were registered, adding that no tsunami warning was issued in connection with the quake activity.
The tremor rattled the capital Port-de-Prince, sparking emotion among residents still reeling from the massive 2010 earthquake that left at least 200,000 people dead and 300,000 more wounded.
"I urge the population to remain calm," President Jovenel Moise said on Twitter, adding that local and regional authorities were assisting those in need and that some damage had been reported.
Prime Minister Jean-Henry Ceant is heading up an inter-ministerial disaster response task force, he said on Twitter.
"The injured are being treated at area hospitals," the civil protection agency said late Saturday, noting that some of the injuries were sustained when people panicked after the quake.
The agency confirmed that some homes were destroyed or damaged, without offering specific figures.
Images of damaged homes and partially destroyed buildings were circulating on social media, but AFP was not immediately able to confirm their authenticity.
The Nord-Ouest department is the poorest part of impoverished Haiti, with many isolated areas due to the dire state of the roads.
The devastating 7.0-magnitude quake in January 2010 left more than 1.5 people homeless. Tens of thousands remain in makeshift camps.
The damage caused was worth an estimated 120 percent of GDP in Haiti, the poorest country in the western hemisphere.
Longer-term reconstruction has been hampered by lingering political chaos in the nation of nearly 11 million people, and by a deadly cholera epidemic introduced by infected Nepalese UN peacekeepers sent in after the quake.