The 44-year-old "Heroes" co-star was arrested last month for allegedly driving under the influence on a Los Angeles freeway. Police said they pulled him over after they spotted him speeding and driving erratically.
E! News said Pasdar's attorney entered the innocent plea Wednesday on the actor's behalf.
A preliminary hearing in the case has been scheduled for March 15, E! News said.
Pasdar is married to Dixie Chicks singer Natalie Maines.