Sanctions cases are extremely specialized and most general business lawyers have zero experience dealing with OFAC, the wrong move can freeze your assets for months or worse. A sanctions attorney in the USA who knows how to communicate with the Treasury Department and build a case for removal from the list can be found here https://arkadybukhlawfirm.com/practice-areas/sanctions-law/ofac-sanctions/ . Do not try to move money around or hide accounts right now, that turns a legal headache into a criminal one overnight.

Check whether your bank has already frozen any accounts, and request a written explanation from them if they have. That letter becomes part of the record your lawyer can use to challenge the action, so do not delete it.