Many people were killed when suspected members of the Boko Haram attacked a funeral procession in Maiduguri, the Borno State capital.
The attack is believed to have occurred on Sunday, with the presidency saying "tens of mourners" were killed.
Maiduguri is considered the safest part of Borno State, but attacks by the Boko Haram still occur in and around the city.
In a statement on Sunday night, presidential aide, Garba Shehu, said President Muhammadu Buhari strongly condemned the attack on the mourners.
The president has received assurances from the armed forces that the terrorists who committed these killings "will pay a big price for their action," Mr Shehu said.
"The federal government is firmly and resolutely committed to taking all necessary measures to safeguard the nation's security. This administration is determined to end the menace of terrorism," the spokesperson quoted Mr Buhari as saying.
He said a major exercise has begun to hunt down the attackers with air patrols by the nation's Air Force and ground operations by the army.
The president assures the residents of Maiduguri and the citizens settled in IDP camps that they will receive increased protection from further attacks by the assailants, Mr Shehu said.
The latest attack occurs about 10 years since the Boko Haram insurgency began in Borno State.
The insurgency has led to tens of thousands of deaths and the displacement of about two million people.
Many of the displaced persons live in internally displaced persons' camps in Borno State. About 30 of such camps are believed to be in Borno, a majority in Maiduguri.
The Boko Haram, which wants to establish an Islamic caliphate in northern Nigeria, has carried out several attacks across Northern Nigeria including in Abuja.
The group's activities have, however, been limited to Adamawa, Borno and Yobe by security operatives since 2016.
Despite the efforts of the security services, however, the group is still able to carry out attacks on civilians and soldiers in the three affected states.