Presidential spokesman Femi Adesina quoted Buhari as saying this at the Presidential Villa in Abuja on Monday when he received the U.S. Secretary of State, Rex Tillerson.
Tillerson arrived in Nairobi on Friday as part of a five-nation tour of Africa that includes Ethiopia, Chad, Nigeria and Djibouti. He flies to Abuja, Nigeria later Monday.
The top USA diplomat is expected to grant press interview immediately after meeting with President Buhari before departing Nigeria for Washington later today. Tillerson says the visa restrictions were necessary because of "all the conflict that exists on Chad's borders".
On the outskirts of a sprawling reserve of Kenyan grasslands where endangered animals roam wild, U.S. Secretary of State Rex Tillerson lavished praise on an American-funded forensics lab that tracks down elephant-poachers for prosecution, and urged aggressive action in Africa on conservation.
When he arrived on Friday, the Secretary of State and the President discussed democracy and media freedom - he said the government should not stifle the media and threaten the courts.
At the time, Trump national security adviser H.R. McMaster said Chad could be off the list "maybe in a couple of months". Trade between both countries stand at 9 billion USA dollars.
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We gave away 16 penalties, which is far too many, and when we got momentum we didn't convert it to points. "That's what it's going to take to win everything next week".
Mr Tillerson was also accompanied on the visit by his Chief of Staff, Margaret Peterlin; Colonel John Walker, as well as the U.S. Ambassador to Nigeria, Mr Stuart Symington.
Chad past year was stunned to find itself on one of six mainly-Muslim countries whose countries are affected by President Donald Trump's travel ban.
The trip hasn't been easy for Tillerson.
But the African tour has coincided with the shock announcement of a possible summit between North Korean leader Kim Jong Un and US President Donald Trump over the nuclear standoff in the Korean peninsula.
The State Department said Tillerson was forced to skip out on some events Saturday, after not feeling well.