The Premier League title-holders are looking to strengthen their squad as they prepare for Champions League football next term and they had earmarked Alex Sandro as a valuable potential addition.
Chelsea were reportedly willing to pay up to €60 million ($88M) for the left wing-back, but Juventus have no intention of parting with the Brazil international.
"Our desire is to not sell any of our most important players," Marotta told Corriere dello Sport.
"We said no to a very good offer from Chelsea for Alex Sandro.
"But we know that we are competing with clubs that are in a position to offer wages that are not rational for us. And players are always their own boss.
"I do not know how Alex Sandro reacted."
The 26-year-old has a contract with Juventus until June 2020.