The apology was for saying its nationals were involved in a failed coup attempt last month.
Gunmen attempted to storm the presidential palace in the beachside capital of the West African nation overnight on December 30 while Jammeh was abroad, but were repelled by guards.
In the immediate aftermath of the coup, Jammeh accused foreign-backed dissidents in Britain, the United States and Germany of mounting the attack.
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However, on Sunday he withdrew the reference to Britons.
"So far there is not a single Gambian or dissidents from Britain who came to join to them (the coup plotters); so I am very sorry," Jammeh said on Monday in a speech before the armed forces near his palace.
Prosecutors in the United States have charged a Texas businessman with bankrolling and trying to lead the coup with the support of a former U.S. Army sergeant. No details of any German involvement in the coup have emerged so far.
Gambia, whose borders are fabled to have been fixed by cannonballs fired from a British warship on the eponymous river, is a popular destination for European tourists.
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But despite the economic ties, 49-year-old Jammeh, who seized power in a 1994 coup, faces growing Western pressure over alleged human rights abuses.
In an apparent jab at the former coloniser, Jammeh said in the same speech: "If God says so I will be very happy to rule Britain. After all they ruled us, so if I can rule them; if Gambia can rule them, that will be the biggest gift."
Jammeh, who typically wears a large white African tunic called a boubou and carries prayer beads, has earned a reputation in the West for colourful speeches.
He once claimed publicly to have personally found a cure for AIDS and told the BBC that he would rule for "a billion years".