Diamond, 26, had the arthroscopic surgery done by Dr. David Altchek in New York, according to Twins general manager Terry Ryan.
"He'll be ready for Spring Training," Ryan said. "But he will not participate in the World Baseball Classic."
Diamond was set to play for Team Canada in the Classic after a breakout season in 2012. The Guelph, Ontario, native led the club with 12 wins while posting a 3.54 ERA in 27 starts totaling 173 innings. He also reached the 200-inning mark for the first time in his career, as he pitched 34 2/3 innings at Triple-A Rochester before being called up in May.
Diamond entered the offseason as the only pitcher guaranteed a spot in the rotation for '13. Since then, however, the Twins have added Vance Worley, Kevin Correia and Mike Pelfrey to the rotation.