Mourinho was only able to recruit three new players during the off-season, despite giving executive vice-chairman Ed Woodward a list of targets he wanted to sign.
"That's football management," Mourinho told Sky Sports.
"I think football is changing and probably football managers should be called more now head coaches.
"We have big multi-functional coaching staff and I think we are more the head coach than the manager, that's the way I think football is going.
"I think it will be a difficult season for everybody, not just for us. But for us it will be a difficult season.
"I had my plans, and I had my plans for many months, and I find myself in the beginning of the Premier League with the market closed and I find myself in a situation which I thought was not a situation I thought I was going to be in.
"But I think it is the last time I speak about it.
"It's over, it's finished, the market is closed."