The Reds won 1-0 at Girona thanks to Salah's goal.
Romeu said afterwards: "We managed the game the way we thought we had to, trying to stop them running at us because they're probably the best there is at that. Unfortunately, we couldn't create enough chances to put more pressure on them towards the end.
"Against these type of teams you have to be very good in both boxes and I think they were probably better than us at defending crosses and creating end product. We weren't, and that's something we have to learn.
"As long as we are alive we'll fight for it. That's the way we are. We as a club have to keep growing and showing our ambition."
Girona wing-back Miguel Gutierrez also said: "We went toe-to-toe with Liverpool and they are a superb team. We even had a share of chances which we didn't finish. But we can be proud of our performance.
"I don't know what it was that was missing in the converting of our chances but we didn't put them away. The match would have been different if we'd gone ahead.
"This is an apprenticeship. We're playing every three days, all over Europe, and that gives you huge experience. But listen, we aren't out yet, this isn't finished. Until we can't mathematically qualify we'll fight."