Her show took place on Saturday in Abu Dhabi. Photos posted on various websites show the singer posing on white marble, dressed fully in black, with her hair covered according to the mosque's guidelines.
The mosque statement, published Monday in local newspapers, said Rihanna was in an area normally off limits for visitors.
It says the fashion-style photo session violated rules on the "status and sanctity of the mosque." The mosque is a major tourist site in the United Arab Emirates' capital.