The Sunderland left-back was withdrawn from Sunderland's starting line-up for Sunday's game against Tottenham after the club received the results of a standard cardiology scan just 40 minutes before the scheduled kick-off, with the club claiming the decision was taken on Football Association advice.
Moyes has now put the issue to rest after revealing the results of new cardiology tests on the player came back all clear.
"There was some misunderstanding with it, but it was only a misunderstanding with what was passed on," said Moyes.
"But I can only confirm that the right decision was taken on the information that we were given, through the doctor, through the club. We acted on the best interests of the boy. He's had tests and spoken with the cardiologists and they've said 'go ahead and get on with things'."
Pictures have since emerged of Van Aanholt, who insisted he has no health problems following the incident, smoking a shisha pipe while on holiday in the summer, and Moyes admits such behaviour is not acceptable.
"I don't expect a player to do that, I don't expect a player playing for me to do that," said Moyes. "I have had a word with him. I am not impressed.
"But I have got to also say it's a picture that comes out maybe six weeks ago, it was in his off-time, it wasn't during the season.
"But just let me make sure, in no way do I condone it at all. I think it's a bad thing for us to show our younger children and for supporters who follow the players. I don't think it's a good thing, I don't think it's a good thing at all."
Moyes added: "They have to be super-fit. I think we need to get Sunderland super-fit and in a great condition to compete and be ready for the games. That's the first thing I need, so I am concerned with that.
"But I also think they are role models now to so many kids. Football is watched everywhere, all over the world, things are done with Twitter and all the other things now and you have to be very careful how you behave.
"It's a short career as well so if you are a player, you earn really good money being a professional footballer, it's a great life. You know something? It's not too big a deal just to make sure you look after yourself for the time you are in it."