Tom Cleverley criticism condemned by Everton manager Roberto Martinez, who labels petition against Manchester United midfielder 'aggressive'

The Everton manager, Roberto Martinez, has condemned the baiting of Tom Cleverley as damaging to the player and something that would happen in no country other than England.

Although the Manchester United midfielder did not play in Wednesday's friendly against Denmark, he was booed when he was named as one of the substitutes. The 24-year-old, whom Martinez managed at Wigan, is the subject of an online petition urging Roy Hodgson not to take him to the World Cup. The petition, set up by Glenn McConnell, an England fan from Blackpool, has attracted 15,000 signatures.

"I don't understand it, I just don't," said Martinez. "Tom is part of a new generation of outstanding English talent. There are only a few English players who have had the sort of education where they look as if they could have been brought up in Holland, France or Spain. Tom is part of that.

"My disappointment is that he is being judged so aggressively. He is still growing. In other countries you wouldn't get this. You would judge someone at 28 or 29 – that is when you would expect such strong opinions. But for a young man to have such pressure, it's incredible."

Martinez, for whom Cleverley played 19 League matches while on loan from United three seasons ago, described him as "a level-headed boy". However, he warned that the sustained abuse could do his career long-term damage. "It will have a huge impact," he said. "Psychologically, you need to be perfect to play in those big games and that will affect your preparation. I hope it won't force him to hide or look away. I think it will be the opposite; he is going to be motivated to be as good as he can be. But I do not understand that sort of scrutiny of a young player."