Witherspoon sat down with ABC's George Stephanopoulos on "Good Morning America" on Thursday. She had issued an apology following the arrest, but Thursday's interview was the first since her husband's DUI stop April 19 in Atlanta.
During the interview, the actress repeatedly apologized for her behavior during the arrest.
The police report says Witherspoon asked a Georgia state trooper, "Do you know my name?" and added, "You're about to find out who I am."
Witherspoon said she had "one too many" glasses of wine, and panicked after she and her husband, Hollywood agent Jim Toth, were pulled over.
"I saw him arresting my husband and I literally panicked," she said. "I said all kinds of crazy things. I told him I was pregnant. I'm not pregnant."
Witherspoon, 37, was arrested after the trooper said she wouldn't stay in the car while her husband was given a field sobriety test.
"I was so disrespectful to him," Witherspoon said. "I have police officers in my family. I work with police officers every day. I know better. It's just unacceptable."
Toth was charged with drunken driving and is due in court May 23. Witherspoon faces a May 22 court hearing on a disorderly conduct charge.
Witherspoon and Toth married in March 2011 after a year of dating. They have a son, Tennessee James Toth. Witherspoon also has two other children, daughter Ava, 13, and son Deacon, 9, from her previous marriage to actor Ryan Phillippe.
The actress said she learned many lessons from this incident, one of which is to obey instructions from police.
Witherspoon, now starring in the movie "Mud," had been in Atlanta to work on the film "The Good Lie."
The Associated Press and ABC News contributed to this report.