Compliance with OFAC is not exclusive to the financial/banking industry. All US persons and entities are prohibited from engaging in ANY transaction that violates OFAC sanctions.
From the OFAC website:
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Who must comply with OFAC regulations?
All U.S. persons must comply with OFAC regulations, including all U.S. citizens and permanent resident aliens regardless of where they are located, all persons and entities within the United States, all U.S. incorporated entities and their foreign branches. In the cases of certain programs, such as those regarding Cuba and North Korea, all foreign subsidiaries owned or controlled by U.S. companies also must comply. Certain programs also require foreign persons in possession of U.S. origin goods to comply. [09-10-02]
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Here is the link to US Treasury OFAC website that gives all the information you ever wanted to know...and then some!
US Treas OFAC Info