The FBI declined a recent White House request to deny media reports about contact between campaign staff for US President Donald Trump and Russian intelligence before last year's election, CNN reported.
The broadcaster cited US officials as saying that the Trump administration had asked the agency to intervene.
Such a request was unusual as it contravenes restrictions on such contacts between the White House and the FBI on pending investigations, it said.
The New York Times and CNN reported earlier this month that Trump campaign staff, including former campaign chairman Paul Manafort, had had "repeated contacts" with senior Russian intelligence officials during the year before Trump's surprise election victory.
One White House official told CNN the request had only been made after the FBI had indicated it believed the reports were inaccurate.
White House Press Secretary Sean Spicer also said CNN had mischaracterised the request.
"We didn't try to knock the story down. We asked them to tell the truth," he was quoted by CNN as saying.
