TAMPA — A conservative advocacy group is asking a federal court to overturn Tampa's ban on conversion therapy for minors.

The City Council approved an ordinance in March that bars the controversial practice, which tries to change a person's sexual orientation or gender identity. Therapists and counselors who offer the therapy to minors face a $1,000 fine for a first offense and a $5,000 penalty for subsequent violations.

Liberty Counsel filed the suit on behalf of two therapists who claim the city's ban violates their First Amendment rights. The suit also contends that only states can regulate counseling, not local governments.

"It is unthinkable that the city and local government would tell a counselor that he or she can not help a client reach a certain objective or goal that the client desires," said Mat Staver, founder and chairman of Liberty Counsel.

Chief Assistant City Attorney Jerry Gewirtz declined to comment on the lawsuit, saying the city does not discuss pending litigation.

If the suit succeeds, advocates of conversion therapy say it would knock out bans already approved in other Florida cities.

In October, Oakland Park was the latest city in the state to forbid the practice. While Miami-Dade rejected a countywide ban, Miami and Miami Beach have instituted citywide bans.

Later this month, the Palm Beach County Commission will vote on an ordinance similar to those already in effect in several of its east coast cities — Boca Raton, West Palm Beach, Lake Worth, Boynton Beach and Delray Beach.

The two therapists named in the Tampa lawsuit claim they are unable to take on new clients or treat current ones here who have "unwanted sexual attractions," Staver said. He said both counselors have offices in the city, but the therapists appear to be based outside the state.

Robert L. Vazzo is a licensed counselor in California, Nevada, Ohio and Florida. But on a website where Vazzo advertises service he lists only Las Vegas and Culver City, California offices.

Vazzo declined comment for this story, directing inquiries to Liberty Counsel.

The other therapist, David Pickup, is licensed to counsel in California and Texas. Pickup is not yet able to practice in Florida, according to the lawsuit. But he already has clients "lining up," he said.

"The City of Tampa is now abusing these children by making therapy illegal," Pickup said. "The longer their rights are taken away, the more likely it is for their anxiety, depression or suicide ideation to increase."

Many in the field say conversion therapy is junk counseling.

Fabrienne McDowell, a psychotherapist and licensed sex therapist who has worked in Tampa since 2010, said conversion therapy is damaging to adolescents.

"Conversion therapy tries to make these young people something that they are not,'' McDowell said. "It tries to change them but they are not changed. It can lead to depression and suicidal thoughts."

This is not the first time Liberty Counsel has found itself in the middle of an LGBTQ issue. The Orlando-based organization represented Kim Davis, the Kentucky court clerk who made headlines in 2015 after refusing to issue marriage licenses to gay couples.

And in May, the Liberty Counsel accused a Riverview High School teacher of forbidding religious jewelry in class and pushing a "pro-LGBTQ agenda" on her students. The teacher was cleared of wrongdoing by Hillsborough school officials.

Contact Jonathan Capriel at jcapriel@tampabay.com. Follow @jonathancapriel.