Michael Bond, 88, the author of the popular books, has not yet seen the movie and is said to have not been consulted over the big screen version, which is due out later this month.
The British Board of Film Classification (BBFC) posted the rating on its website, saying there was “dangerous behaviour, mild threat, mild sex references (and) mild bad language”.
It warns that “parents should consider whether ... content may upset younger, or more sensitive, children” on films awarded a Parental Guidance (PG) certificate.
Bond, who makes a cameo appearance in the film, directed by Paul King, told the Daily Mail: “I’m totally amazed.”
“I’d be very upset. I might not sleep well tonight. I can’t imagine what the sex references are. It doesn’t enter into it with the books, certainly,” he said.
Ben Whishaw voices the Peruvian bear in the live-action film, which also features starring roles for Hugh Bonneville, Peter Capaldi and Nicole Kidman.
Whishaw replaced Colin Firth as the voice of Paddington after The King’s Speech star quit, saying he was having trouble finding the voice of the marmalade-loving bear.
The film sees Paddington despatched from his native jungle, and smuggled on board a boat to England.
Recent children’s films which have been awarded a Universal certificate include The Lego Movie, Despicable Me 2 and Monsters University, while Frozen (mild threat) and How To Train Your Dragon 2 (mild violence and threat) were awarded a PG certificate.
Bond’s books have sold 35 million copies worldwide since they were first published in 1958.