Nigeria's President Goodluck Jonathan appealed for more U.S. help in fighting Boko Haram, as the Islamists struck again on Saturday and called for a boycott of upcoming general elections.
The head of state for the first time claimed direct links between the Sunni radicals who have been waging a six-year insurgency in Nigeria and the Islamic State group in Syria and Iraq.
He told the Wall Street Journal in an interview: "Are they (the United States) not fighting ISIS? Why can't they come to Nigeria?
"They are our friends. If Nigeria has a problem, then I expect the U.S. to come and assist us."
But Pentagon spokesman Rear Admiral John Kirby said there are no plans to send U.S. troops to Nigeria.
"I can tell you that there are no plans as I speak here to send unilaterally, to send or to add U.S. troops into Nigeria. There are no U.S. troops operating in Nigeria," he told reporters.
Kirby said the United States was in the early phases of helping establish a multi-national task force of African nations to help Nigeria defeat Boko Haram.
Jonathan's comments were published as hundreds of Islamist fighters invaded the northeastern city of Gombe, firing heavy guns and throwing leaflets calling for locals to shun the elections.
The attack saw residents flee and the authorities impose a 24-hour lock-down in the city, which Boko Haram has repeatedly targeted.
Nigeria's defense headquarters said it had repelled the attack.
"The terrorists attack on Gombe has been repelled. Troops are in pursuit," it said on Twitter.
Boko Haram has opened up two new fronts in its campaign to create a hardline Islamic state in northeast Nigeria, pushing into neighboring Niger last week and, for the first time on Friday, into Chad.
It has also increased the frequency and intensity of its attacks on northern Cameroon. The increasing regional threat has led to the deployment of troops from all three neighboring countries, reflecting security fears.
Jonathan and his government have long sought to portray the insurgency as being fueled by outside forces and he has previously called Boko Haram "Al-Qaida in west Africa."