Authorities seized the vessel and the undeclared weaponry in the Panamanian port of Manzanillo Monday night, CNN reported.
Panamanian Security Minister Jose Raul Mulino told CNN the ship had arrived from Cuba.
The type of weaponry found wasn't clear, officials said. A U.N. resolution, approved in response to the country's nuclear activities, bans North Korean import and export of most weapons.
Mulino said the North Korean crew of 35 resisted arrest and the ship's captain attempted to commit suicide.
Panamanian officials said they will ask a U.N. technical support team to inspect the cargo to determine what type of weaponry was found.