The Esbern Snare warship, which has been patrolling the pirate-infested waters since early August, responded to a distress call from a ship traveling through the Gulf of Aden. The name and home port of the ship were not immediately available.
A spokesman for the navy said the helicopter reached the pirates before they were able to board the vessel on Saturday. The helicopter fired warning shots to stop the pirates as they were attempting to flee to the mainland.
The Danes took nine of the pirates aboard the Esbern Snare, later releasing them, the spokesman said.