The 26-year-old actress' intimate pictures are said to have been hacked from her phone. One, which she is believed to have taken herself, shows her topless, reported Daily Mail online.
Johansson is the latest celebrity whose mobile phone, emails and computers have been hacked into by a gang.
The authenticity of the pictures could not be verified, but sources close to Johansson say she has called in the FBI over the "criminal act".
Spokesperson for both Johansson and the FBI declined to comment on the issue.
Other stars who have been the victim of the hacking include Jessica Alba, 30, singer Christina Aguilera, 30, Disney star Demi Lovato, 19, and singer/actresses Selena Gomez, 19, and Miley Cyrus, 18 and Mila Kunis.
Published 15 September 2011, 06:19 IST