In terms of the ACH Network, all U.S. ACH participants, including Originators, Originating Depository Financial Institutions (ODFI), Receiving Depository Financial Institutions (RDFI), Receivers and third-parties need to be aware that they can be held accountable for sanctions violations by the U.S. Government.
The NACHA Rule reflects the "Know Your Customer" priciple that the ODFI will verify the Originator is not a blocked party and that a good faith effort will be undertaken to determine through the normal course of business that the Originator is not engaged in transmitting funds to, from, or on behalf of a party subject to a blocking action. The same goes for RDFI's.
In conclusion, for the safety of your institution, it would be wise to perform some sort of check against the OFAC listing.