United were dumped out of the Champions League after a 3-0 humbling by Barcelona on Tuesday night and the Norwegian has admitted it could take him years to replicate the Red Devils past successes.
"We know there's work to be done," Solskjaer told Sky Sports. "I've said all along this isn't going to change overnight and the next few years are going to be massive to get to the level of Barcelona.
"We're on with the job and we've spoken to the players about it as well. We need to create an environment of top, world-class attitude every single day.
"We've got a lot of good players to work with but as I have said, we have a rebuilding job. It started with coaches, players and of course one or two additions in the summer."