Pirates seized a Greek-owned cargo ship off the coast of Somalia late on Thursday.
The Titan with 24 crew was sailing from the Black Sea to Korea when it was attacked.
Last month, pirates seized a Greek-owned cargo ship, with 22 crew off Somalia.
In January, pirates seized another Greek vessel off the coast of Cameroon and killed its captain.
EU forces foiled a pirate attack on a Greek-flagged crude oil tanker off the coast of Somalia in the same month.
The coast off Somalia is one of the world's busiest shipping areas.
Warships from more than a dozen nations, including Britain, the United States, France, Germany and Iran are patrolling the Gulf of Aden in an attempt to deter the pirates.