E! News said Singer sent a cease-and-desist letter to numerous gossip outlets that posted the sexy self-portraits, which were apparently hacked from the star's cellphone and leaked online.
Singer demanded in the letter the Web sites remove the "stolen, copyright-protected private photographs" immediately or face a lawsuit.
"The highly personal and private photographs at issue capture our client self-posing in her own home in a state of undress and/or topless," Singer said in the letter. "If you fail to comply, you will be acting at your own peril. Please govern yourselves accordingly."
E! News said the FBI is investigating whether the "Lost in Translation," "Vicky Cristina Barcelona" and "Girl with a Pearl Earring" actress is the target of a hacking ring that has been stealing pictures and videos and leaking them on the Internet.