Jose Mourinho is under fire at Old Trafford after a slow start to the season, with his team sitting eighth in the table and seven points off the pace.
Fred, away on international duty with Brazil, said it was understandable why there was so much focus on United.
"Manchester United is a huge team, so, if results are not coming, people and the press will wonder why, for sure," he said on Tuesday.
"They'll think something is wrong, so that's normal, that's a pressure you have anywhere, in a company, if results don't show up.
"And Man United is not different, with such the quality and importance they have. Of course, it's always good to wear the national squad shirt and in the meantime, when we're here, we try to forget a bit about there and try to focus only on here."
Fred arrived at United from Shakhtar Donetsk in June and has made seven appearances for his new club.
"I'm very happy in this new life I'm having, at this new club, adapting. That's a bit different for me but very nice," Fred said.
"They help me a lot to adapt and in everything, to learn English. This is very important for me.
"The championship is very different from the one I was playing before, so I'm trying to adapt as fast as I can, watch the players when they're training, the way they work, the positions they have.
"I guess this makes it easier for me to get adapted. I hope to keep strong and focused to play more with Manchester."