United have netted just five times in the Premier League this season, ahead of only promoted side Southampton.
The 30-year-old Portuguese attacking midfielder scored 54 goals in 166 Premier League appearances for United but has yet to score in this league campaign.
"As for the club, I want to improve as soon as I get there, and make sure the goals start coming again," Fernandes told Portuguese media ahead of Portugal's Nations League match against Poland.
"I have to take responsibility for that too because I'm a midfielder who scores a lot of goals, and over the years, I've always been at a very high level in terms of goals, and I have to live up to that, with those expectations. I also have my own standards, I don't hold back on that.
"I haven't scored for the club yet and I hope that as soon as I get there, I can score and help the club get back to winning ways and to a good level."
United next host 11th-placed Brentford on October 19. United are 14th in the standings with eight points from seven matches, with the Old Trafford side suffering their worst start to a season in the Premier League era.
