A spokesman for the Philippine foreign ministry told reporters that the Japanese-owned Stella Maris was seized by pirates on Sunday.
He said officials had been in contact with the sailors, who were in a good state of health.
But he added that it was against the Philippine government's policy to pay a ransom to the kidnappers.
The Stella Maris, which was carrying a cargo of lead and zinc, was boarded by 38 armed men in the Gulf of Aden, according to the Spanish news agency EFE.
The seas off Somalia have some of the highest rates of piracy in the world.
The country has not had a functioning national government since 1991 and has been wracked by civil strife.