Comey nevertheless did not make any major new revelations about alleged links between Trump or his associates and Russian Federation, an issue that has dogged the president's first months in office and distracted from his policy goals such as overhauling the US healthcare system and making tax cuts.
Before Trump fired him, Comey ran the FBI investigation of possible Kremlin collusion with the Trump campaign in the 2016 election.
When asked about whether he had recordings of his conversations with Mr Comey, which he has previously hinted, the president said he would address it at a later date.
Asked directly if Comey lied before the Senate intelligence committee when he testified that Trump asked for the pledge and that the probe be deep-sixed, the president did not use that word.
"My common sense told me, he's looking to get something in exchange for granting my request to stay in the job, ' said Mr Comey".
Mr Comey maintains Mr Trump fired him because of the Russian Federation inquiry. Who would ask a man to pledge allegiance under oath?
Pentagon gets authority to set troop levels in Afghanistan
"We are not winning in Afghanistan right now and we will correct this as soon as possible", Mattis said in his testimony. Republican Senator John McCain , the chair of the committee, agreed that Congress needs to pass a budget.
Mr Trump refused to say whether those private exchanges were taped, a matter at the heart of the conflicting accounts of what passed between them.
He also denied that Comey's version of the events of a February 14 meeting, in which Trump said that he "hoped" that the FBI director could let go of an investigation into former National Security Adviser Michael Flynn. Yesterday showed no collusion, no obstruction.
The brief news conference - where each President will take two questions from the press - comes the day after James Comey's bombshell Capitol Hill testimony in which the fired Federal Bureau of Investigation director accused the White House of "lies". "And some of the things that he said just weren't true". If Comey felt that was inappropriate, he should have said something right then and there. Comey's testimony Thursday was part of that investigation.
During nearly three hours of statements Thursday before the Senate Intelligence Committee, Comey described himself as "stunned" by Trump's "very disturbing" and "very concerning" behavior in several of their meetings.
"One hundred per cent", Mr Trump said.
Speculation over the tapes is rooted in a particularly cryptic tweet from the USA president issued nearly a month ago, seeming to suggest he might hold recordings of the conversations.