UsMagazine.com said John fell ill during his performance Sunday at The Colosseum in Las Vegas and his condition worsened despite medication and rest.
He was hospitalized at Cedars-Sinai Wednesday morning and underwent a battery of tests.
"Those tests resulted in the attending physician recommending that Elton not perform any concerts for approximately seven days with complete rest and antibiotic treatment to cure his respiratory infection and prevent any damage," his representative told UsMagazine.com Thursday.
"All I can say to the fans is sorry I can't be with you. I hope to see you soon at this wonderful theater at Caesars Palace," John said in a statement.
The recording artist began a three-year residency at the famed hotel and casino last fall.