Boko Haram has killed thousands of people over the last year in its campaign to revive a medieval Islamic caliphate and is seen as the worst security threat to Nigeria, Africa's most populous country and biggest energy producer. Boko Haram has also launched cross-border attacks into Cameroon and Niger.
The West African bloc known as ECOWAS will seek the support of the African Union (AU) for the idea of a regional military force, Mahama told a news conference.
"Nigeria is taking military action and Cameroon is fighting Boko Haram, but I think we are increasingly getting to the point where probably a regional or a multinational force is coming into consideration," said Mahama, who currently chairs ECOWAS.
"It is what we want to discuss at the AU because, if that must happen, there must be a mandate to allow such a force to operate," he said.
Boko Haram militants seized the military base and town of Baga, in Nigeria on the shores of Lake Chad, on Jan. 3.
Baga was the headquarters of a planned force to fight the insurgents announced last October with troops from Nigeria, Chad, Niger and Cameroon, but that initiative stalled.
Boko Haram's insurgency has stirred increasing international outrage, particularly when militants seized more than 200 school girls from a school in Chibok, northeastern Nigeria - the epicentre of the violence - in April last year.
France must do more to help countries fight Boko Haram, President Francois Hollande told an annual conference of French and foreign ambassadors in Paris.
"Today, Cameroon, Niger, Chad and Benin are threatened and this situation means the international community must take appropriate action and can't let this be," he said.
France said last month it would help coordinate a regional task force against Boko Haram given signs of mistrust among West African neighbours.
Cameroon President Paul Biya this month appealed for military help against Boko Haram. On Friday, U.S. Ambassador Michael Stephen Hoza said Washington would help train Cameroon's soldiers and offered equipment for the fight.
Russian Ambassador Nikolay Ratsiborinski said Moscow would supply equipment, training and arms to Cameroon and provide humanitarian assistance.
