Peter Busch of an NBC station in Fort Myers, Florida, reported on Friday that Phelps "had a change of heart" and would be training for the 2016 Games.
Busch's father, Frank Busch, is the director of the US national swim team.
Still, Phelps downplayed the suggestion.
"Do people really believe everything they hear or read? There are too many people in the world that think they have a 'story,'" he tweeted.
As recently as March, Phelps ruled out a return, saying in Rio while attending the Laureus Sports Awards that he wouldn't compete again.
"I'm done, I'm done," Phelps said on March 11.
Phelps, the most decorated Olympian of all time with 22 medals, retired from swimming after bagging four golds and two silvers at last year's London Games.
He finished his Olympic career with an astonishing 18 gold medals, including his unprecedented eight at the 2008 Beijing Games.