Robertson enjoyed a fine afternoon and got his name on the scoresheet but he felt he should have had a spot-kick in the second half.
He was brought down by Johann Berg Gudmundsson in the box but replays showed the Iceland international got a toe to the ball before swiping Robertson's legs.
The left-back was infuriated that the challenge was overlooked and could not believe that VAR did not overturn the decision.
After the match, BT Sport captured the moment he confronted the officials to question their performance, reports the Daily Express.
"How that's not a penalty? That's an absolute disgrace," Robertson could be heard saying.
"What's the point in having it [VAR]?
"Wait until you see it, you'll go 'how the f*** is that not a penalty?'
"You didn't see f****** anything? You didn't see anything apart from the f****** booking in the last minute.
"F*** me, what's the point in having yous?
"What's the point of having yous in the middle."
By this point Jurgen Klopp had joined him and said: "We have to be honest."
The rest of the German's comments were not clear due to the background noise.