"A diagnostic arthroscopic intervention is necessary to solve the current problem of overload on the right knee," the club said in a statement.
The 27-year-old United States-born forward complained of discomfort in the knee last month and did not play in Fiorentina's opening Serie A match of the season on Saturday when they lost 2-0 to AS Roma.
Rossi, arguably Italy's most clinical and reliable forward when he is fully fit, was left out of the World Cup squad because then coach Cesare Prandelli felt he had not fully recovered from an operation in January.
The injury saga began in 2011 when Rossi suffered an anterior cruciate ligament injury while playing for Villarreal in a Spanish league match against Real Madrid.
He fought desperately to be fit again in time for Euro 2012, only to re-injure the knee in training the following April, causing him to miss the tournament.
He made an excellent comeback with Fiorentina last season, scoring 14 goals by early January to make him Serie A's leading scorer.
However, he then suffered a less serious injury, a second degree sprain to the medial collateral ligament in the same knee.
Although he returned to action in May and played in a friendly against Ireland, it was not enough to win him a World Cup place.
(Writing by Brian Homewood in Berne, editing by Ed Osmond)
Share
