Hargreaves, who joined rivals Manchester City as a free agent in the close season after four years in the red half of the city where he made just 39 appearances, said injections he had received had hampered his recovery from knee problems.
“We’ve been trying to analyse all the stuff he’s said this morning and we are going to have a club statement to address that,” Ferguson told a news conference.
“But as far as I’m concerned…my medical staff are one of the main reasons Manchester United have been so successful in the last few years. There is absolutely no doubt about that. We have fantastic medical staff and great sports scientists.
“That’s my opinion of Manchester United and that’s more important than what anyone else has got to stay about that.
Canadian-born Hargreaves, whose career has been blighted by chronic tendinitis in his knees requiring surgery, was critical of his former club in comments reported by local media but was urged by current boss Roberto Mancini not to dwell on the past.
“I received some injections and my tendon was never the same,” said Hargreaves, who moved to United from Bayern Munich for 17 million pounds in 2007 despite having broken his leg.
“I tried to get back on my feet and (United’s medical staff) said my tendon was good, but it felt like I was made of glass.
“(The injections) obviously had a huge impact. With hindsight, I probably should not have had them. It’s difficult.
“I’ve had to be a guinea pig for a lot of treatments.”
Hargreaves, 30, made his first appearance for his new club this week, marking the occasion with a stunning goal in the 2-0 victory over Birmingham City in the League Cup and Mancini said he should be concentrating on the future.
“I think for him now it is important to play often and to train without problems, I think the past is the past,” the Italian told a news conference, adding that he was “absolutely”sure United had not got the player’s treatment wrong.
“He was unlucky because he had three or four injuries but for now I think it is important that he can see only the future.”
Hargreaves had also suggested he was pressured into playing against Wolverhampton Wanderers last season, his only appearance last term which lasted just five minutes before he limped off with a hamstring injury.
“I said: ‘I think I’ve got a bit of a muscle problem here’,”Hargreaves said.
“I was surprised it didn’t go in the warm-up. I wasn’t going to sprint, which sounds comical. I was just going to try to get through 45 minutes because that would have been a start.
“But I didn’t even last five. I wasn’t surprised because I had said to them that I had a hamstring problem, which I obviously did have.”
Hargreaves has won 42 England caps, played at the 2002 World Cup and was outstanding at the 2006 finals. He won the Champions League and Premier League in his first season with United but then spent most of his time in the treatment room.
He famously posted videos of himself on YouTube carrying out exercise and mobility drills to prove his fitness shortly before securing his move across town to City.
He played 57 minutes against Birmingham on Wednesday and Mancini said it was important for him to now get more match time under his belt after such a long time on the sidelines.
“Now he needs to train, to recover and to play,” he said.“Maybe every five or six days he needs to play one game, not Premier League maybe, and after he will see.”
Asked if Hargreaves was ready to play two matches in a week as many players have to, Mancini replied: “Now I don’t think so but maybe in three or four weeks it will be possible, why not?”