A hair salon in west London put up a giant poster of the North Korean leader in its window after reading unconfirmed media reports that men in the reclusive Asian state had been ordered to have the same hairdo.
The promotional poster read: "Bad Hair Day? 15 percent off all gent cuts through the month of April."
With its shaved sides and bowl-like shape, Kim Jong Un's distinctive haircut has been a light-hearted talking point for North Korea watchers.
But officials at the country's embassy, which is just a short walk away from the salon, visited to complain and wrote to the Foreign Office asking it to take "necessary action" to stop "the provocation," a British diplomatic source said.
The source said the Foreign Office was considering its response.
The embassy, located in a semi-detached house near the hair salon, filed a complaint to the police too.
A spokeswoman for London's Metropolitan police said on Wednesday that the complaint had been investigated and that no action would be taken.
"We spoke to all parties involved and there were no offences," the spokeswoman said.
Officials at the embassy could not immediately be contacted for comment.
David Burrowes, a lawmaker from Prime Minister David Cameron's Conservative party who specializes in North Korean issues, said the incident was amusing but sinister.