Goal.com revealed in March that the 27-year-old, whose contract expires in 2015, has already admitted to teammates that he may leave Old Trafford this summer.
"Wayne Rooney is one of the best attackers in the world," Ancelotti told reporters. "I think it will be impossible for PSG to buy him. He is an idol at Manchester United."
Rooney was left out of Manchester United's starting lineup for its Champions League tie against Real Madrid last month, prompting uncertainty over his future at the club, but Sir Alex Ferguson later insisted that the decision was for tactical reasons and his relationship with the striker was fine.
PSG has been heavily linked as a potential destination for Rooney, despite the French club's director, Leonardo, and president, Nasser Al-Khelaifi, both dismissing reports which suggest a bid had already been made for the England international.
On Sunday, PSG's former adviser Michael Moulin, who owns French sports publication Le 10 Sport, claimed a deal for Rooney to move to the Ligue 1 leaders has already been completed.
“I announce to you from trusted sources: Rooney to PSG is done. He will be at PSG next season,” he said.