The Blues skipper is disappointed at the performance of his team but believes they can turn the tie around in the second leg next week at Old Trafford
Blues midfielder Ramires was brought down by Patrice Evra in the final moments of added time in the first-leg of the quarter-final clash at Stamford Bridge on Wednesday night.
But Spanish referee Alberto Undiano Mallenco waved play on and United will take a 1-0 advantage into the second leg at Old Trafford next Tuesday thanks to Wayne Rooney's 24th minute strike.
Terry, the Chelsea captain, believes it was a “clear” penalty but said afterwards that he could not speak his mind for fear of Uefa sanctions.
He said: “It was clear. Even from 50 or 60 yards away I could see Ramires got the first touch. After the game, we watched it on the video like everyone else.
“I think the most frustrating thing for the players is that we can't come out here and be honest about it. We would face possible bans, we're seeing players receiving bans left, right and centre for speaking honestly after games.
“You guys lose out, the players can't be honest and we end up walking on eggshells. Unfortunately I can't say more about it but it was a clear penalty.”
The 30-year-old defender admits the Londoners were disappointed with their performance but insists his side can turn the tie around in Manchester next week and also haul in the 11-point gap between the sides in the Premier League.
Terry added: “I can 100 per cent see us turning the tie around.
“We're frustrated with the result and losing the game but the manager stressed after the game that it's only half-time and we're right in the tie.
“It's disappointing as we were at home tonight. We expected a better performance considering we were at home but we've got the quality to go up there and win the game. We did it in the league last year.
“They know we're still in it and we certainly do as well.
“We're also still in the title race – we realise we're many points away but we've got one of the strongest squads in the league and everybody is now fully fit.”