The head of the censor board, Pahlaj Nihalani, told Indian media that it was because the film was "too scary".
The Jungle Book is a computer-generated remake of the 1967 animated film that was based on Rudyard Kipling's book.
The film, which has been praised in early reviews, releases in India on 8 April.
Mr Nihalani told an Indian newspaper that the decision was taken because "the 3D effects are so scary that the animals seem to jump right at the audience".
The music composer of the film, Vishal Bhardwaj, told a press conference that nothing about it warranted a U/A certificate.
"It is such a beautiful film. There is nothing in it which will scare the kids, but let's just accept the fact, these are the times," he was quoted as saying by the media.
The decision has predictably led to some ridicule on social media.
The film has also received a Parental Guidance (PG) certificate in the US, which has led to this debate among two Indian film reviewers:
India's censor board has given Disney's Jungle Book a U/A certificate, meaning that children will not be able to watch the film without adult supervision.