"I think we had our moments in the first 25 minutes, their goal-keeper has made four fantastic saves," the United boss told Sky Sports after the match.
"Then they missed a penalty kick. That would have made a big difference to the game, I think, it would have made it a bit more nervous for us.
"But it's a European quarter-final and Roma are second top in the Italian league, you expect them to produce something in the game and I think they grew in confidence a bit.
"But I think in the main we've made some fantastic chances, their goal-keeper's had I don't know how many good saves at the end of the game.
"We are just pleased to be there."