The England youngster was sent off by referee Mark Halsey just before half time, following a challenge on United defender Jonny Evans.
Ferguson told BBC Sport: “Jonjo Shelvey’s sending off was a clear red card, there was a dangerous attempt to go for the ball.
“Jonny Evans went for the ball and got it, and I don’t think there was any other decision referee could make.”
United won 2-1 against Liverpool.
