Spicer accused reporters of continuing "to perpetuate a false narrative" by not covering statements that could seem favorable to Trump and argued that the statements by the House and Senate Intelligence committees were not based on any investigative work.
A spokesperson for GCHQ, the British intelligence agency that Napolitano referred to, denied the report.
“Recent allegations made by media commentator Judge Andrew Napolitano about GCHQ being asked to conduct 'wire tapping' against the then president elect are nonsense," the spokesperson said in a press release. "They are utterly ridiculous and should be ignored.”
Spicer also asserted that House Intelligence Committee Chairman Devin Nunes still stands in the administration's corner, despite his statement yesterday contradicting the president's wiretapping claim.
"I don't believe just in the last week of time, the people we've talked to — I don't think there was an actual tap of Trump Tower," Nunes said.
During the press conference, Spicer reiterated that Trump's use of the term "wiretapping" was all-encompassing.
In that interview, Trump said he didn't necessarily mean "wiretapping."
"When I say 'wiretapping,' those words were in quotes. That really covers, because wiretapping is pretty old-fashioned stuff, but that really covers surveillance and many other things," he said.
Two of Trump's four March 4 tweets related to wiretapping include the term in quotes.
ABC News' Mike Trew contributed to this report.