There were reports that the 43-year-old actress, who is engaged to Justin Theroux, is expecting a baby girl which is due in May next year, reported the New York Post.
"It's just another fabrication! She was just at LACMA and she certainly does not look pregnant. When has Star (the magazine) ever been right?," her representative said.
Aniston, who wore a cleavage-baring gown, had showed some skin while posting next to her fiance at the LACMA 2012 Art + Film gala on October 27 in Los Angeles.
Other stars who attended the event included Cameron Diaz, Robert Pattinson, Drew Barrymore and husband Will Kopelman, Evan Rachel Wood and husband Jamie Bell.