Had you been logging in through VPN? Was there an IP address leak?

You have two choices. Neither are good. Either declare to them that you are a "Prohibited Person" (resident of Cuba) or take the ballsy approach of trying to produce fake (non Cuban) documents and an explanation for your login activity.

Playing games (the second choice) is usually a good way to get your money confiscated. However to be fair, there are Treasury sanctions on Cuba, which puts you in a very sticky situation as Bitfinex cannot knowingly transact with Cubans.

Sorry to see this, it's a bad situation to be in. Hopefully it's not a life changing amount of money.