There were no casualties reported among the 25 crew members onboard, but the Greek-flagged vessel has lost the ability to manoeuvre, UKMTO added.
The vessel reported being approached by two small craft with approximately 15 people onboard and said there was a brief exchange of small arms fire, UKMTO said.
The exchange took place 77 nautical miles (142 km) west of Yemen’s port of Hodeidah, it said.
British security firm Ambrey separately reported an incident in the same area, but did not provide further details.
Delta Tankers, company operating the tanker, was not immediately available for comment.
Ansarullah resistance movement has launched attacks on international shipping near Yemen since last November in solidarity with Palestinians in Israel's war against Gaza.
MNA/PR