Vatican spokesman Matteo Bruni said Francis, 86, does not have COVID-19, but requires several days of therapy.
"The tests showed a respiratory infection (COVID-19 infection excluded) that will require some days of medical therapy," Bruni's statement said.
Francis is receiving treatment Gemelli University Hospital, where he underwent surgery in 2021. His audiences through Friday were canceled, raising questions about Francis' participation during the Vatican's Holy Week activities starting Sunday.
Francis appeared in relatively good form during his regularly scheduled general audience Wednesday, though he grimaced strongly while getting into and out of the "popemobile."
Francis had part of one lung removed when he was a young man due to a respiratory infection, and he often speaks in a whisper.
He spent 10 days at the Gemelli hospital following the 2021 surgery for an intestinal narrowing, which included the removal of 33 centimeters (13 inches) of his colon.
Francis is due to celebrate Palm Sunday this weekend, kicking off the Vatican's Holy Week observances: Holy Thursday, Good Friday, the Easter Vigil and finally Easter Sunday on April 9.
He has used a wheelchair for over a year due to strained ligaments in his right knee and a small knee fracture. He has said the injury was healing and been walking more with a cane of late.
Francis also has said he resisted having surgery for the knee problems because he didn't respond well to general anesthesia during the 2021 intestinal surgery.
He said soon after the surgery that he had recovered fully and could eat normally. But in a Jan. 24 interview with The Associated Press, Francis said his diverticulosis, or bulges in the intestinal wall, had "returned."