Video showed the one-time "Star Wars" leading lady slurring her words and singing off-key while her dog defecates on the stage of the Holland America Eurodam luxury liner in the Caribbean last week.
Fisher, 56, was featured on the cruise as a surprise celebrity guest.
TMZ said Wednesday buzz among attendees of the show was the recovering alcoholic and drug addict was intoxicated at the time.
But her representative told the celebrity news website her strange behavior was related to her bipolar disorder.
"There was a medical incident related to Carrie Fisher's bipolar disorder. She went to the hospital briefly to adjust her medication and is feeling much better now," the publicist told TMZ.
She has been in the news in recent months as fans and the media speculate about whether she will reprise her role of Princess Leia in the upcoming "Star Wars" sequels.