That's a striking change from his comments immediately after the London Games, when he insisted his retirement was set in stone and it had always been his goal to quit swimming before he turned 30.
Phelps will be 31 at the time of the opening ceremony for the Rio Games.
"I don't know. We're in 2013," he said, while adding, "There's nothing in the works."
There's plenty of time for a comeback. Phelps would likely want to begin training before the end of the year, which would allow him to get into peak condition leading up to the next world championships in 2015, an important stepping stone for the Olympics.
Phelps certainly isn't training at the moment.
He jammed the small toe of his right foot on the edge of a sofa while at home in Baltimore, and aggravated the injury when he played in a golf tournament at Lake Tahoe.
He's wearing a boot cast on his foot while in Barcelona.
After some sightseeing and promotional appearances, Phelps took in a second night of swimming at the Palau Sant Jordi before heading back to the US yesterday. He's accompanied by his new girlfriend, Golf Channel reporter Win McMurry.
Phelps was still seething about the US loss in the 4x100-metre freestyle relay on Sunday. The American were edged at the finish by the French, a repeat of last summer's Olympics when a team that included Phelps also settled for silver.
He said the Americans should have gone with a different lineup, using Jimmy Feigen in the leadoff spot and Nathan Adrian as the anchor. Instead, Adrian went first and Feigen took over for the finish despite being the least experienced member of the US foursome.
"We should never lose that race," said Phelps.
- AP
