Friedrich resigned Friday over telling the Social Democrat party that parliament member Sebastian Edathy, a Social Democrat, was being investigated for alleged involvement in child pornography, the BBC reported.
Edathy denied any wrongdoing, but resigned from parliament.
The leak was made to the party last year and Friedrich may be prosecuted over the incident.
In in resignation announcement Friday, Friedrich said he believes he acted "correctly -- in both the political and legal senses."
German Chancellor Angela Merkel said she accepted Friedrich's resignation with "great respect and great regret."