Rooney was seen limping at a promotional event at Old Trafford on Monday, prompting speculation that he is struggling for fitness ahead of the Manchester derby.
However, Pellegrini claims that United have more than enough quality to cope in the absence of their captain.
"I think Rooney is a very important player for Manchester United but I think that big teams never depend on one player," the Chilean told Sky Sports News.
"They have enough important, creative players to replace him."
Sunday's derby is scheduled to get underway at 1.30pm.