A spokesman for the Islamist group said "Britons and Turks" staged the operation in which commandos rappelled from a helicopter as they tried to storm a house belonging to a senior Shebab commander in the southern Somali port of Barawe.
"There is no British involvement," a spokeswoman for Britain's Ministry of Defence told AFP when asked to comment on the raid.
She would not give any further details.
The assault comes two weeks after Shebab gunmen attacked Kenya's Westgate shopping mall, massacring 67 people in a four-day siege.