Having just read a few Nigerian papers on this item, there is no mention that the ship was Iranian and no suggestion that the items were on their way to Gaza. In fact, the tenor of reports suggests fears that the arms had reached their destination and were intended for local use. Also they were intercepted last July.
Tropical storm Erika weakens, but leaves 20 dead in Caribbean (AP)
from the article: Nigeria intercepts 13 Iran missile containers possibly destined for Gaza