The photographs, which show a woman taking snaps of her nude body, surfaced on the internet on Tuesday.
Lively's spokesperson has publicly denied the legitimacy of the pictures, branding the images as "100% fake".
"Blake has never taken nude photos of herself," the rep said. "Blake will pursue legal action against the publication which initially published these photographs and any other outlets that republish them in any manner."
Lively, who is believed to be dating Leonardo DiCaprio, recently admitted that tabloid coverage of her personal life does serve to increase Gossip Girl's ratings, adding: "It makes sense to draw parallels between the show and what goes on in my real life."
The Green Lantern, in which Lively co-stars with Ryan Reynolds, is released in US and UK cinemas on June 17.
