The 32-year-old was substituted in the 1-0 win over Arsenal prior to the international break after a collision with David de Gea.
Moyes confirmed the defender had been given the week off to recuperate, adding that he was hopeful Vidic would be able to come back into the team at the Cardiff City Stadium.
"We've given him a chance to recover. We'll bring him back and hopefully he’ll be fine," the Scot said on Friday.
"He's had a bad concussion, everyone saw he had a bad knock. But that's why you have a big squad at Manchester United so when injuries come around you're able to cope.
"Concussion is something you have to be careful with."
Reigning champions United are on an unbeaten run of nine games in all competitions, a sequence that includes their home victory over Premier League leaders Arsenal last time out.
Moyes is keen for his side to continue their strong form in South Wales, adding that he never doubted their quality, even after they dropped points against the likes of Southampton, West Brom and Shakhtar Donetsk.
"We're on a good run, we have confidence about us and we want to keep that going," he added.
"We came off a couple of good results and sometimes you want the games to come thick and fast. You can't do anything about the international break, whether you win or lose going into it.
"I never thought we were out of (the title race). We just go about our job and try to win each game."
