Chenoweth was attempting to board a flight departing from Dallas when an attendant refused her entry because she said the actress didn't have the proper paperwork to take her dog Maddie, People magazine reported Friday.
The employee scolded Chenoweth in front of the other passengers at the boarding gate, though Chenoweth insisted she had the correct paperwork.
Another gate agent saw a mistake had been made and allowed the actress and Maddie to board, People said.
"American Airlines: Dallas flight attnt supervisor: Ms Kidwell. Abuse not ok," Chenoweth tweeted Tuesday, adding the hashtag "#tripfromhell" at the end.
A representative for American Airlines told TMZ the company regrets the incident.
"We have been in touch with Ms. Chenoweth to offer our apologies for the misunderstanding," the representative said. "We refunded the [$125] cabin pet charge as soon as we realized the mistake. We hope she will consider flying American again in the future."