Social media users last week pointed out that the pope's account, "franciscus," appeared to have given the sign of approval to a photo of Brazilian bikini model Natalia Garibotto wearing a racy outfit. The Vatican said Frances himself wasn't responsible.
"The issue is currently being investigated in close contact with The Holy See," a Facebook spokesperson told Fox News.
A Vatican official confirmed Friday that the "like" did not come from the Holy See and that the Vatican is working with Instagram to determine what happened.
The pope has 7.4 million followers on Instagram.
The Associated Press contributed to this report.