The 23-year-old left-back joined United from Dutch club Vitesse on a five-year contract earlier this week.
"We see him as an aggressive player who knows himself," he told Voetbal International. "He always looks at the future.
"We brought him in because of his potential. It's not without reason that he is on the brink of playing in the Dutch squad.
"That's why I said 'Buttner, that's not a bad player' when [Sir Alex] Ferguson asked me about him."
Buttner was part of Vitesse's first team from 2008 to 2012.