The stance came in response to an online petition with more than 120,000 signatures seeking a ban on such therapy.
The petition was started Jan. 3 on the White House's website, days after Leelah Alcorn, a transgender 17-year-old, committed suicide. In her suicide note, the teen said that, among other measures, her parents took her to religious therapists who refused to accept her identity as a girl.
"Therapists that engage in the attempt to brainwash or reverse any child's gender identity or sexual orientation are seriously unethical and legislation is needed to end such practices that are resulting in LGBTQ+ deaths," the petition says.
The White House said it "fully supports efforts" toward such a ban.
"We share your concern about its potentially devastating effects on the lives of transgender as well as gay, lesbian, bisexual and queer youth," Valerie Jarrett, senior advisor to President Obama, said in the White House response to the petition.
"The overwhelming scientific evidence demonstrates that conversion therapy, especially when it is practiced on young people, is neither medically nor ethically appropriate and can cause substantial harm," she said.
Medical groups have also come out against such therapy.
"Since homosexuality is not a disorder or a disease, it does not require a cure. There is no medical indication for changing sexual orientation," the director of the Pan American Health Organization said in 2012, adding that conversion therapy represents "a serious threat to the health and well-being — even the lives — of affected people."
California, New Jersey and the District of Columbia have banned licensed professionals from practicing conversion therapy on minors.
California's ban was signed into law in 2012 and took effect in 2014. Since last year, 18 other states have introduced similar legislation, according to the White House's statement.
A national ban would require congressional action.
Lawmakers in California are trying to do more to eliminate what they call a harmful practice.
Last month, state Sen.
"Many of these facilities have operated without regulation or any type of oversight," he said.