The Portuguese coach is unbeaten in three matches as United boss but the coach knows that the "storm will come" for his team at some stage.
Speaking ahead of United's Premier League trip to Arsenal on Wednesday (04.12.24), Amorim said: "We are going to have difficult moments and we will be found out in some games, I know that.
"I know it is really hard to be a Manchester United coach and say these things in press conferences - and we want to win all the time, no matter what - but we know we are in a different point compared to Arsenal.
"I would like to say different things, but I have to say again, the storm will come."
Amorim praised the job done by his counterpart Mikel Arteta in transforming the Gunners into title contenders since he took charge in 2019.
He said: "[He has done] an amazing job. Sometimes coaches are judged just with titles, but what he has been doing with Arsenal is amazing.
"He transformed the team, he bought some youngsters that are now a big talent in this country. I hope to have the same mindset that he had in difficult moments because I followed the Premier League for a long time and it is a very good characteristic in Mikel. He is doing a great job."
Amorim believes that the faith Arsenal have shown in Arteta has been key to the team's success in recent years but accepts that United chiefs may not be so forgiving if goes through a rough patch.
He said: "That is always important for a coach, to have that confidence.
"We have to acknowledge that Manchester United is a little bit different, all the attention you guys [journalists] put here all the time, we will try to do things a bit faster.
"There is massive attention here and massive judgement every day."