The man grabbed hold of a child's bag outside Heronsgate School in Lichfield Down, Walnut Tree, at about 08:20 GMT on Wednesday.
The man said, "you're coming with me" before the pupil broke free.
"The incident has been reported to police who are now investigating," the school said. The offender is said to be white and in his 30s.
He had blonde hair and a scratch on his left cheek. He was wearing blue jeans, a blue-green t-shirt and Converse trainers.
A man tried to abduct a boy outside a primary school in Milton Keynes, the school said.