The 22-year-old was part of the Blues team that beat United earlier in the season and also had success in his days at Wigan Athletic.
"My last game against United was when we beat them 5-4 in the Capital One Cup," Moses told The Sun. "The time before was for Wigan at the end of last season when we won 1-0.
"That game was like a dream for me because we knew if we lost we'd probably get relegated and it was the best we played all season.
"But this game is not just about beating Manchester United. It is about winning the FA Cup again for Chelsea."
Moses has been in good form for the Blues this season, scoring six goals in 29 appearances in all competitions.