The Cypriot-flagged "Monchegorsk" has been docked off the Mediterranean island for a week while authorities carried out checks on its cargo.
The United States had said it was carrying arms-related material in violation of U.N. sanctions on Iran.
A team of Cypriot experts carried out two inspections of the ship, a statement from the Cyprus Foreign Ministry said.
"The Republic of Cyprus today submitted a report on the findings of the inspections to the competent U.N. Security Council Sanctions Committee," it said.
Cyprus has refused to say what is on board the cargo vessel, docked off the Cypriot southern port of Limassol under police guard since Jan. 29.
However, a Western diplomatic source said U.S. Navy inspections had found arms-related material including propellant and other casings for artillery and tank rounds, as well as shell casing.
Before its detention in Cyprus, which as flag state has responsibility over the ship, the Monchegorsk had been boarded by the U.S. Navy in the Red Sea.
U.S. officials had last week said they had found weapons on board the cargo vessel, which for legal reasons could not be confiscated. (Reporting by Michele Kambas, editing by Alison Williams)
