The assault cost 33-year-old Damian Vincent a total of £700 in a court fine and costs.
The youngster and two friends were on bikes in Newmarket when the incident happened, Boston Magistrates’ Court heard on Wednesday (October 16).
Michael Little, prosecuting, said the van was waiting to pull out at a junction when the boys were forced to take evasive action and swerve around it.
Then, the van pulled alongside the boys and Vincent shouted abuse.
“Mr Vincent got out and his manner was aggressive. After a few words, with the palm of a hand he slapped [the boy] around the left cheek.
“This caused the boy’s glasses to fall off. Mr Vincent then got back into the van and it drove off.
“[The boy] was able to take a photo of the van on his phone and that is how inquiries were able to progress.”
Mr Little said an independent witness described Vincent throwing a right hook in an unprovoked attack.
Vincent, a self-employed joiner from Kingston Drive, Ollerton, pleaded guilty to assault on July 3.
In mitigation, solicitor Dav Naghen said the defendant was a father-of-two and there was shock about the incident from his friends and family because it was so out of character.
Vincent was fined £400 and told to pay £85 costs and £40 victim surcharge.
He was ordered to pay a total of £175 compensation for damage to the glasses and injury to the victim, who cannot be named due to a court order.