Onana denied Eddie Nketiah and Ismaila Sarr with a stunning double-save in the second-half.
"I think it is not so important," he told Sky Sports afterwards. "Because we didn't win. We are such a big club, when we go somewhere, I think we have the ambition to try to win. We didn't win but I'm happy for the work and for the sacrifice of my team-mates. I feel we were better than them. We had so many chances but, unfortunately, didn't score. It's difficult to go back with one point when we deserved to win.
"One hundred per cent, it's always nice to keep a clean sheet but the most important thing, especially playing for Manchester United, you have to win. We didn't lose today but we came here with the mentality (to win) so we go home disappointed."
Onana continued: "Football, sometimes, you cannot control everything.
"We were dominant, we had more chances. I had faith, always in my guys. We hit the bar twice and, hopefully, in the coming games, we will score a lot.
"We had an important game for us to win but I go back home sad because Manchester United, everywhere we go, we have to play good football, we have to win, we have to be dominant, create chances and we have to finish."