The incident occurred while the Boeing 737 was on the tarmac at Seattle-Tacoma International Airport, Washington state, and was preparing for a flight to Burbank, California.
Amber Nelson, a passenger on the flight, wrote on her Facebook page that the attendant had been demonstrating how to use a life vest when the passenger -- who was seated between two women -- called out, "Ooh, sexy!"
"Before we could do more than glare in his direction, the flight attendant removed her vest, purposely walked up to him and said, 'You need to be respectful,' and started to walk back to her task," Nelson wrote. "He said, 'C'mon, I'm just playing with you!' "
Alaska Airlines spokeswoman Ann Zaninovich confirmed Nelson's account of the events to Alaska Dispatch News but did not have additional details on the incident that took place on Sunday.
Zaninovich said the airline backed the flight crew's initiative in handling the situation.
"We stand behind the actions taken by our employees," Zaninovich was quoted as saying.