"We are looking to bring in players as there are significant areas we want to strengthen," he said ahead of the derby at Old Trafford on Sunday.
"We will not go for second best. If we have to wait a bit longer, then so be it.
"We want to make sure when we go into the market we get the right quality and the right type of player.
"United have been able to build over 15-20 years with the help of Champions League money. They have world class players in back up positions. We are nowhere near that. It does take time.
"We are very much at the beginning of where we want to go. United are at a place where they are very happy to be for quite some time."