In an early morning tweet that came after a barrage of criticism for the way the White House had repeatedly changed the details of its story over the firing of Mr Comey, the president said that because of his busy schedule and with lots of things happening, it was not "possible for my surrogates to stand at podium with flawless accuracy".
Spicer was eventually asked if Trump's tweet means that he "doesn't have the full picture" when standing at the press briefing podium.
In the tweet, Trump also warned Comey about leaking to the press: "James Comey better hope that there are no "tapes" of our conversations before he starts leaking to the press!"
The White House, however, declined repeatedly on Friday to discuss the matter - including whether there are recording devices in the Oval Office.
Mr Trump's firing of Mr Comey already has left him with the dubious distinction of being the first president since Nixon to fire a law enforcement official overseeing an investigation tied to the White House.
Trump says Comey had told him three times he was not under investigation in the Russian Federation probe.
Mr Trump told NBC he had planned to fire Mr Comey all along, regardless of whether top Justice Department officials recommended the stunning step.
Spicer, who kept his answers short during the briefing and largely dodged specific questions about Trump's meeting with Comey, did say at one point that he was not aware that any recording of the Trump-Comey meeting exists.More news: Will Ferrell makes students laugh at USC commencement speech
Spicer also denied reports that Trump solicited a loyalty pledge from Comey during their dinner earlier this year.
In his short letter to Comey, Trump made a specific point of mentioning that he "appreciated" how the FBI told him three times he was not personally under investigation over Russian Federation.
The controversy began this morning, when Trump again took aim at the investigation into his administration and its potential ties to Russian Federation, while blasting the "fake media" and its coverage of the issue.
As described by the two people, the dinner offers a window into Trump's approach to the presidency, through Comey's eyes.
Earlier Thursday, on Capitol Hill, acting FBI Director Andrew McCabe strongly disputed the White House's assertion that Comey had been fired in part because he had lost the confidence of the FBI's own rank-and-file.
In addition to any possible tapes, the two congressmen request "all documents, memoranda, analyses, emails, and other communications relating to the President's decision to dismiss Director Comey" by May 25. The veiled threat added to the storm over Trump's abrupt firing of Comey on Tuesday. Everything is on the up and up, though, because Attorney General Jeff Sessions recommended Comey's firing-the same Jeff Sessions who had to recuse himself from the Russia/Trump campaign investigation because he lied during his confirmation hearing.
Asked at Wednesday's White House news briefing whether loyalty was a factor in picking a new Federal Bureau of Investigation director, Sanders said Trump wanted someone who is "loyal to the justice system".