The Anadolu news agency reported, citing the text of the lawsuit, that Ince's remark was false and an attack on Erdogan.
Erdogan's lawyers have demanded compensation in the amount of some $21,000, the news outlet stated.
Earlier in the month, media reported that Ince had inquired about Erdogan's 2001 visit to the US state of Pennsylvania, where Gulen has been living since 1999.
Ankara accuses Gulen's movement of masterminding the attempted coup of July 2016, and has arrested thousands of military personnel, activists, officials, journalists, legal and educational workers over suspected links to the group. Gulen, who has been residing in the United States since 1999, refuted the allegations on numerous occasions.