A file photo shows an illustration made with figurines set up in front of Facebook's homepage. AFP/Joel Sage
The group said in a statement Monday that if Facebook fails to comply by September 4, it will sue the California company.
Facebook representatives in Germany didn't immediately respond to an email requesting comment.
German privacy rules have posed a legal headache for Facebook, Google and other foreign web giants in recent years. The country has strict laws on data protection that give consumers significant rights to limit the way companies use their information.