The State Department said Friday it is concerned about reports that Iran's parliament is considering legislation to require non-Muslims in the country to wear badges.
Spokesman Sean McCormack said any such measure would be "despicable" and carry "clear echoes of Germany under Hitler."
US government statistics indicate that 98 percent of Iranians are Islamic. Other faiths are Zoroastrian, Jewish, Christian, and Baha'i.
McCormack said he could not comment further because the precise nature of the proposal is unclear.
"I don't have all the facts," he said.