The film star's representative told UsMagazine.com the wedding report is a "total fabrication" and said Aniston "was not in Greece" scouting locations for a possible ceremony.
"How is it that one of the most photographed people in the world supposedly goes to Greece to check out a hotel she never heard of and is not spotted or photographed?" the representative told the celebrity news Web site.
Aniston and Theroux have been dating for nearly a year.
'Maze Runner' tops the North American box office
'Maze Runner' brings in $11.3M Friday