Deadline.com reported the lawsuit is in response to an essay Heard penned for The Washington Post in December in which she discussed being a victim of domestic abuse, but did not mention Depp by name.
Heard previously accused Depp in 2016 of assaulting her during their brief marriage.
Depp has denied the allegations, stating in his lawsuit, "They were part of an elaborate hoax to generate positive publicity for Ms. Heard and advance her career."
Depp said his ex-wife's public remarks have cost him work and damaged his reputation.
Heard's lawyer Eric M. George issued a statement to People magazine response to Depp's legal move.
"This frivolous action is just the latest of Johnny Depp's repeated efforts to silence Amber Heard," George said.
"She will not be silenced," the attorney added. "Mr. Depp's actions prove he is unable to accept the truth of his ongoing abusive behavior. But while he appears hell-bent on achieving self-destruction, we will prevail in defeating this groundless lawsuit and ending the continued vile harassment of my client by Mr. Depp and his legal team."
Depp, 55, and Heard, 32, met on the set of the 2011 film The Rum Diary, married in February 2015 and were officially divorced by January 2017, UsMagazine.com said.