The Dutchman could feature in Saturday's Premier League match at home to West Bromwich Albion but the even better news for the English champions is his return in time for Wednesday's tricky trip to Shakhtar Donetsk in the Champions League.
"Robin will be back involved somewhere," Moyes told a news conference. "Whether we use him, whether we don't, he's trained today, so he's match fit but we'll see exactly where he is."
Van Persie, the Premier League's top scorer last term with 26 goals which propelled United to a 20th league title, missed Sunday's derby humiliation at the Etihad stadium when Moyes said he had been a big loss.
United's failings were repeatedly exposed by their merciless neighbours and even though Wayne Rooney worked hard to try to create something, he could not be in two places at the same time to assist and finish.
Van Persie's return provides that lethal final touch or moment of brilliance that can dig United out of a hole even when the rest of the team are under-performing.
It was left to Javier Hernandez to rescue them on Wednesday as the Mexican scored the winner in a 1-0 victory over a dominant Liverpool in the League Cup and Moyes could turn to him again if he wants to give Van Persie more rest before the European game.
Midfielder Tom Cleverley, who came on as a substitute against City and missed the Liverpool match, has also returned to training after picking up a knock.
"He is not too serious. He sort of rocked his knee in training, and we were a bit worried, but he has had no reaction from it," Moyes said.
"He has done some training today and hopefully he won't be too far away tomorrow either."
Moyes has often spoken of the tricky start United were handed in the fixture list and having faced Chelsea, Liverpool and City in their first five league games, picking up just one point from those matches, he has been on a steep learning curve.
It was always going to be the case, coming in as a former Everton manager who had not won a trophy in 11 years on Merseyside and taking over from Alex Ferguson, whose 26 years at Old Trafford were full of silverware.
"I have been learning every week since the day I walked in as Manchester United manager," he said. "I learned something the first day and I have continued to learn since.
"I don't think that is going to change for a long time. I even think the manager who has just left was continually learning in the job. I am relatively new to it so I am still learning everything about it.
"I think if you are playing big games, that is part of it. This club has always played in big games, in big finals and games that really matter. The games this week mattered. In some of them, we did better than the others."
His side entertain West Brom on Saturday (1400 GMT) with Steve Clarke's team having picked up their first league win of the season last weekend in a 3-0 victory over Sunderland.