Trailing 3-0 from the first leg, City were ahead inside two minutes through Gabriel Jesus and bombarded Liverpool in the first half in search of more goals.

They thought they had a second shortly before half-time when a loose ball bounced off Liverpool's James Milner for Leroy Sane to turn in, but the goal was wrongly ruled out for offside.

A furious Guardiola marched onto the pitch after the game to remonstrate with the Spanish referee but was told to sit in the stands for the second half and Liverpool went on to win 2-1 on the night.

"I said it was a goal. That's why he sent me off," Guardiola told a news conference. "It was the difference between going in at half-time 1-0 and 2-0."

He added: "If you go in 2-0 at half-time it's a little bit different and when [the ball] came off Milner, it can't be offside.

Speaking just after the final whistle to BT Sport, Guardiola said the referee overreacted in sending him to the stands.

"I said it was a goal. I didn't insult him. I was polite, I was correct," Guardiola said. "But Mateu Lahoz is a special guy. He likes to be different, he likes to be special ... when everybody sees the things, he's going to decide the opposite.

"It's too much to send [me] off because I didn't say any wrong word."

City also had penalty shouts when Milner blocked a shot with his arm and Raheem Sterling went down under a challenge from Andrew Robertson.

ANTHONY DEVLIN/AFP/Getty Images

And that's after City were also on the wrong end of some close decisions in the first leg at Anfield, when Mohamed Salah appeared to be marginally offside for the opening goal while a late Gabriel goal was ruled out when he appeared to be onside.

"It's different when the first goal in Anfield is offside," Guardiola said. "These kind of games, this competition the impact is so big. The goal for Gabriel Jesus in Anfield is a goal, it's not offside. It's a penalty from Robertson on Raheem Sterling right in front of the fourth official. Of course that has an influence."

Guardiola admitted he was concerned by the appointment of Mateu after he took charge of City's game against Monaco in the last-16 last season and booked Sergio Aguero for a dive when he was caught by goalkeeper Danijel Subasic in the penalty area.

"Like last season in Monaco when it was a clear penalty with the same referee, these kind of actions when the teams are so equal, the impact is so big," the City boss added.

In the end, Liverpool went through 5-1 on aggregate, and Guardiola said it was a deserved result.

"What I would say is big congratulations for Liverpool -- hopefully they can defend English football in the semifinals," he said. "They are a top team and a top manager. I would say they deserve to be in the semifinal, they made an outstanding 45 minutes."

City have now lost their last three matches -- twice against Liverpool and the defeat to Manchester United in the derby -- but Guardiola said they should be proud of what they have achieved over the season with his side needing just two victories to wrap up the Premier League title.

"We played for 10 months amazingly," he added. "That can happen when you play three top teams. Now we have to go to Tottenham and we have to recover mentally.

"I would say the exception has been the 10 months -- winning, winning, winning -- that is exceptional.

"Today I think the defeat was because after 1-1 it was so tough to go through. That's why I have to try to analyse it game by game."