The local daily Malta Today said the prohibition does not, however, prevent the execution of a contract concluded before the entry into force of the EU sanctions on October 26, 2010.
In Tehran, the Iran News daily said IRISL had signed some two-year contracts in Malta before that date.
The US State Department said IRISL has been setting up shell companies in Malta to try to evade UN and EU sanctions.
The sanctions prohibit the loading and unloading of cargoes from vessels owned or chartered by IRISL in Maltese ports under any new contracts after October 26, 2010.
Malta Today said it located 42 IRISL-owned companies at three addresses ion Malta.