Manchester City boss Pep Guardiola issued a rallying call to the club's supporters to get over their Champions League hang-ups after the resounding 4-0 Group C victory over Borussia Monchengladbach.

Sergio Aguero netted his second hat-trick in as many European appearances this season and Kelechi Iheanacho came off the bench to complete the scoring in stoppage time, crowning the type of serene victory City have seldom enjoyed in the continent's premier competition.

The match was put back 24 hours after a torrential downpour in Manchester forced a postponement on Tuesday and a crowd of 30,270 lapped up the latest thrilling display of Guardiola's tenure.

However, the former Barcelona and Bayern Munich coach was disappointed to see so many spaces in the 55,000-capacity arena for a match that was once again preceded by City supporters booing the Champions League anthem.

That protest has its roots in UEFA's punishment of the Premier League club under Financial Fair Play rules in 2014, compounded by dissatisfaction among fans after some CSKA Moscow supporters attended a 2-2 draw against City at Arena Khimki later that year – a match that was supposed to be played behind closed doors as a sanction for racist behaviour at the Russian club's previous games.

Nevertheless, in keeping with the new era he is fashioning with impressive pace in Manchester, Guardiola has no time for these lingering gripes.

"I was not here, I don't know what happened, but they can forget it. They must forget it," he told a post-match news conference.

"All we can do is play every time better than the day before and the people say, 'wow, I'm going to the Etihad Stadium because I spend 90 minutes there and I have fun.

"Today the stadium is not completely full so the only thing you can do is play good so the people who are at home and watching our games say, 'wow, next time I am going to be there'.

"What happened in the past is the past. Forget about it. We are in this competition and so proud to be in the competition.

"In a few weeks the best football player ever is coming here, with Luis Suarez and Neymar and the amazing team of Barcelona. You have to come here to enjoy it.

"We are going to work until the last moment to convince the people to come here and join us, to watch the Champions League games."

Guardiola has made an effort to ensure City players show appreciation to their supporters at the end of home and away games and, on Champions League nights at the Etihad Stadium, he hopes this becomes a two-way street.

"Our fans, they have to know that we played for them," he said. "It is our job. We are here but to play without our fans is not the reason why we are here.

"Our fans, they have to know that we need them in the Champions League. In the Premier League everybody comes here but in Champions League the people don't come and we need them.

"We cannot make something good in the Champions League in the up-coming years without them. With our supporters we are stronger.

"I think, honestly, what these players have done since the beginning [of the season], in our games at home and away, our players deserve the stadium completely full."