Ferguson said: "It was a marvellous result for us. We showed discipline and composure on the ball.
"Ronaldo's goal changed the game for us. It was a fantastic header.
"His spring and courage to go in front of the defender surprised the Roma player.
"It was a centre forward's header - it reminded me of myself."
On Park's contribution to the second goal, Ferguson said: "I'm not sure how he managed to get the ball back into the area. It did not seem possible.
"But Wayne appeared to unsettle the goalkeeper and managed to touch it in."
There was no repeat of the violent scenes that have marred clashes between the clubs in recent games, and Ferguson said: "That is a bonus and what we wanted to happen tonight.
"Roma and ourselves have worked hard to make sure there would be no incidents."