Jurgen Klopp was left furious that referee Martin Atkinson failed to award Liverpool a penalty for an apparent handball against Shane Long.
Long scored a late winner in Wednesday's second leg at Anfield to secure Southampton a 2-0 aggregate victory as the Reds crashed out of the EFL Cup semi-final.
However, the outcome could have been different had Atkinson awarded the hosts a penalty for Long's handball.
And while Klopp conceded that this side should have done more with the chances they created, he felt that the match official was wrong in his call to wave away his side's protests.
The German claimed it was not the first time his side had been denied an obvious decision by the officials this season and was unable to hide his frustration.
"The ref did not see the handball of Long and it does not help in a game like this," he told BBC Sport.
"If we could hear a referee's whistle it would be nice. I do not know how many times that has happened this season.
"Against Manchester United we had a clear offside goal [scored against us by Zlatan Ibrahimovic], nobody says anything. Tonight [Wednesday] a penalty, nobody says anything."
On Southampton's win and Liverpool's finishing, he added: "They won both games, they deserved it.
"We did really well, we cannot create more chances than we did in the second half, we were dominant. It is difficult because you have to take risks but too many risks plays to their strengths.
"We had big chances and no luck. A lucky save [from Fraser Forster], a good save but a lucky save.
"We had seven good chances. You have to score, and we did not do so we lost. I am fine with the performance but not the result."