They are upset The Girl with the Dragon Tattoo star has been cast to play a character of Native American origin, revealing that their initial complaint was met with an unapologetic comeback by studio bosses at Warner Bros.
A posting on ThePetitionSite.com reads, "They said a black actress and a French actress were first considered for the role."
The protesters add, "This casting choice is particularly shameful for a children's movie. Telling children their role models must all be white is unacceptable... Tell Warner Bros. to stop casting white actors to play characters originally written as people of color!"
Sources previously told Variety.com that Oscar winner Lupita Nyong'o and Blue is the Warmest Color star Adele Exarchopoulos were considered for the Tiger Lilly role before it was offered to Mara.
The petition against her casting has garnered over 4,500 signatures since its launch on Tuesday (18Mar14).
Pan, which stars Hugh Jackman, Garrett Hedlund and newcomer Levi Miller, is set to hit theatres in 2015.