Buffon was struggling with a thigh injury earlier this week.
"Ours is a nation of conspiracy," director general Beppe Marotta said. "Everything needs to be taken back to sport.
"There is nothing to say on Buffon. He is the captain of Juventus and the captain of Italy. The allegations made are unfounded.
"Wearing the blue shirt of Italy is the highest aspiration for all players and Buffon is not the kind of guy to quit at the first problem.
"He didn't play against Denmark because he thought he wasn't ready to."