Beckham was speaking on CBS about United's poor season.
"It's tough times," he said.
"I don't like seeing some of things that are going on at the club.
"On the pitch is what counts but in all honesty I'm seeing a lot of things that are not okay in my eyes as a fan and as a lover of Man United.
"You have to represent the badge. That's what it is about. I've seen a lot of things where players are not acting in the right manner."
Blast for today's players
Inter Miami co-owner Beckham also questioned the commitment of the players to the club.
He continued: "We were a part of a team that was so well mannered.
"We understood what it meant to play for Manchester United. We understood what the badge meant. Wherever we travelled, whether it was in Europe or in Asia, we respected the fans.
"We respected the fact that they were turning up, paying money and wanting you to sign and take pictures. You respect that."