"Master reports merchant vessel was approached on its starboard bow by 3 small craft, the 3 small craft regrouped astern with a closest point of approach of 1NM," UKMTO said in an advisory note.
The merchant vessel's security team fired warning shots to deter the small craft, and the vessel then proceeded safely to the next port of call, the organisation added.
The Iran-aligned Houthi militants have launched waves of exploding drones and missiles at vessels since Nov. 19 in response to Israel's military operations in Gaza.
U.S. and British warplanes, ships and submarines have responded to the Houthi attacks with dozens of retaliatory strikes across Yemen against Houthi forces.
(Reporting by Hatem Maher; editing by Christina Fincher)
