The Belgian international has not found the back of the net since moving from Everton during the summer, while Manchester City midfielder Yaya Toure has scored 16 times this season.
When asked about his side's threat from that area of the field, Moyes told United's official website: "I take that point. They have got goalscoring midfield players and it's something which is important - to have goalscorers all over the field who can contribute lots of goals.
"We've got good midfield players. I still think Fellaini can get some goals. He was unlucky at West Ham when he could have scored a header and maybe you could argue he deserved a penalty kick when he went through at the end.
"He's beginning to show signs he can get some goals for us as well but I do agree City have very good midfield players who are goalscorers."
United sit seventh in the Premier League.