City lost 4-3 to United on aggregate, thanks to a late goal from United striker Wayne Rooney at Old Trafford on Wednesday.
“United have a big squad and are one of the top sides in the league,” Garrido said.
“They played a strong team, they did not use youngsters, which to me shows how good we are becoming. It means we are doing well.
“City have invested a lot of money in trying to win trophies and we are still involved in the FA Cup.
“We are also trying to get into the top four. It is not easy but we believe we can do it. We have to keep looking forward.”
