The lawsuit, filed in U.S. federal court, alleged that defendants used different companies and websites to sell those fake engagement services, Facebook said Thursday evening.
"By filing the lawsuit, we are sending a message that this kind of fraudulent activity is not tolerated on our services, and we will act to protect the integrity of our platform," Jessica Romero, director of platform enforcement and litigation at Facebook, wrote in a post.
Facebook said it counts 2.7 billion monthly users across its family of apps, which includes Instagram. Earlier this week, the company reported its earnings: Revenue exceeded expectations and the firm matched estimates for its daily active user growth.
The social media platform is undergoing a major transition from News Feed ads, as it seeks to grow advertising revenue from its newer Stories products from services including Instagram, WhatsApp and Messenger.
— CNBC's Salvador Rodriguez contributed to this report.