United visit bitter rivals Liverpool on Sunday, knowing victory will give them a six-point lead over the champions at the top of the table.
Rashford said: “It is going to be a good feeling if we manage to win the league — but if we finish second or third, then it's not going to be a good season for us.
“It is not what we set out to try to do at the beginning of the year."
United go into the clash on an unbeaten run of 11 Prem games, nine of them wins.
England ace Rash, 23, added: “We are a team which is still improving, we are in a good run of form, so we just have to focus on ourselves and do the best we can."
He added: “I believe that we have one of the most versatile squads in the Premier League probably, especially going forward.
“It is exciting but it is still the beginning of something.
“Now we just want to keep progressing and keep improving."