The conservative commentator Ann Coulter unleashed a barrage of criticism about Delta Air Lines on Twitter after she was moved to a different seat on a flight on Saturday, prompting the company to publicly return fire and call her comments “unnecessary and unacceptable.”

Ms. Coulter, a pundit known for headline-grabbing comments, began her attack after a flight from La Guardia Airport in New York to West Palm Beach, Fla.

In a statement on Sunday, the airline described what happened as a “seat mix-up,” but Ms. Coulter excoriated the airline in social media posts after she was removed from a seat that she said she had specifically booked.