The Red Devils have been linked with the Chile international for the majority of the summer, with some reports having suggested that United striker Javier Hernandez could move in the opposite direction.
However, when asked by reporters about those rumours this afternoon, Marotta was adamant that no talks had taken place and he went on to add that the 27-year-old was not for sale.
"They are the usual media rumours that are different to the reality. There is always the same speculation about him. He was never for sale and there have never been any negotiations," he said.
Vidal is yet to feature for Juventus during their pre-season friendlies because he returned to training later than his teammates due to his exploits at the World Cup.