The White House Press Secretary has since said he was referring to the attack in Orlando
White House Press Secretary has made three references to an unknown Atlanta attack, US media reports.
Mr Spicer referenced Atlanta as part of his remarks defending President Trump's executive order on immigration, the Daily Beast revealed.
Speaking on ABC on January 29th, Mr Spicer argued: "What do we say to the family who loses somebody over a [terrorist] - whether it's Atlanta or San Bernardino or the Boston bomber? Those people, each of whom had gone out to a country and then come back."
He made a similar comment on NBC's Morning Joe the following day, suggesting: "There was a very short period of time in which we had something to execute that ensured that the people of the United States were safe. Everybody's been protected. "What happened if we didn't act and somebody was killed?
"Too many of these cases that have happened - whether you're talking about San Bernardino, Atlanta, Boston [...] The answer is we act now to protect the future."
In a press briefing later on the 30th, Mr Spicer said: "We're reviewing the entire process over this period of time to make sure that we do this. But I don't think you have to look any further than the families of the Boston Marathon, in Atlanta, in San Bernardino to ask if we can go further."
Attacks were carried out in Boston and San Bernardino, although not by citizens of the seven countries affected by the travel ban.
According to CNN, meanwhile, the last major terrorist attack in Atlanta was the Centennial Olympic Park bombing in July 1996, which killed one person and injured more than 100 others. Eric Rudolph, born in Florida, was convicted of the attack.
An Atlanta police spokesperson told CNN "we have no record of an Islamic attack in the City of Atlanta."
Asked about the Atlanta references, Mr Spicer told ABC News that he "clearly meant Orlando" - referring to the Pulse nightclub massacre in June 2016.
Earlier this week, Trump aide Kellyanne Conway apologised for her references to a fictitious 'Bowling Green massacre'.
She explained that she was instead aiming to highlight the case of two Iraqi citizens who had been living in Bowling Green, Kentucky. They were sentenced for terrorism offences in 2013.