31 CFR § 560.410 - Provision of services.
(a) The prohibition on the exportation, reexportation, sale or supply of services contained in § 560.204 applies to services performed on behalf of a person in Iran or the Government of Iran or where the benefit of such services is otherwise received in Iran, if such services are performed:
(1) In the United States, or
(c) The prohibitions on transactions involving blocked property contained in § 560.211 apply to services performed in the United States or by U.S. persons, wherever located, including by an overseas branch of an entity located in the United States:
(d) Example. A United States person is engaged in a prohibited exportation of services to Iran when it extends credit to a third-country firm specifically to enable that firm to manufacture goods for sale to Iran or for an entity of the Government of Iran. See also § 560.416.