The club have endured a difficult few weeks and their manager feels it is because some people cannot see they are in transition.
Jose Mourinho believes "people with a brain" should be able to see that Manchester United's recent issues are a result of being in "transition".
Although United have only failed to win four of their last 15 games across all competitions, performances have fallen well short of expectations.
The most striking failure in recent months was the 2-1 defeat at home to Sevilla in the Champions League round of 16, a defeat which eliminated United from Europe's elite competition.
Mourinho came in for significant criticism over United's tactics in the wake of that defeat and he responded with a 12-minute tirade in his news conference before the 2-0 FA Cup win over Brighton.
Much of that rant focused on the expectations of United fans and Mourinho has again addressed the subject of supporters, saying he is convinced anyone with a "brain" should be able to see the team is in a state of flux.
"I understand the frustration, I understand the sadness of being knocked out in the Champions League, but I don't understand anything more than that," Mourinho told CNN.
"In the history of football all around the world, not just in England, you had the biggest clubs with the moments of transition, you have the biggest clubs with moments of continuous and permanent victories and these are phases in the club.
"And I think really at this moment looking to us in the Premier League we have one team [Manchester City], one club clearly better prepared than us in the past few years to be first and we have 18 clubs behind us. One in front of us, 18 behind us.
"Of course in the future, we want to have 19 clubs behind us but this is the reality, and the reality is for people with a brain, with sense, with common sense, with knowledge of what sport is, we are in a moment of transition.
"Being in a moment of transition and still [managing] to do what he did last season and win trophies and to do what we are trying to do this season, which is still trying to win a trophy, and try to be second, because at this moment it's the only top position that is possible for us to get. I think we are in a good position."