Current manager Antonio Conte's side saw their ten-match unbeaten start to the season come to a crunching halt in the last two games, suffering back-to-back defeats to Fiorentina in Serie A and Real Madrid in the UEFA Champions League.
This has led some to speculate on Conte's future but Marotta told a Juventus shareholders' meeting that the club's hierarchy are happy with their current boss.
He said: "The rumours about Prandelli in place of Conte in the future are absolutely unfounded.
"Conte has a contract which expires in 2015 and we have a great relationship with him, we are very pleased with his work."
The future of Gianluigi Buffon has also come under scrutiny after the 35-year-old keeper conceded four goals in 16 minutes against the Viola in the 4-2 defeat in Florence.
Marotta has also sprung to the defence of the club captain, saying: "Buffon? He is a champion, a leader of the locker room and still one of the best goalkeepers in the world.
"Errors happen to everybody. Buffon has a long contract with us, he refused a proposal from a foreign club which offered him double what we pay him."
Marotta also said the club have great relationships with midfielders Arturo Vidal and Claudio Marchisio, and defender Angelo Ogbonna, and will not set buy-out clauses for the trio.
"A buy-out clause for our great players? We have an excellent relationship with Vidal, Marchisio and Ogbonna and we won't set a clause in their contract."