Under fire Haaland can get better: Guardiola
Haaland has netted 30 times this season and scored 52 goals last term when City won the Champions League, Premier League and FA Cup.
However, the 23-year-old failed to score for the third time against Real Madrid over the past two seasons in City's 3-3 draw in their Champions League quarter-final first leg on Tuesday.
Haaland's hold up play was labelled "League Two" standard by former Manchester United captain Roy Keane after a 0-0 draw against Arsenal last month.
Guardiola was quizzed on whether Haaland needed to improve if he is to win the Ballon d'Or, the annual award given to the world's best player.
But the City manager was quick to point to Haaland's record of silverware in less than two years in Manchester.
City have already won the UEFA Super Cup and Club World Cup this season and remain in contention to defend their treble.
"He needs to play more minutes, to learn from what you have to do," Guardiola said at his pre-match press conference before Saturday's Premier League clash against Luton.
"But the target is not the Ballon d'Or, the target is to win trophies and he did. Would we have won five trophies last year without him? Not a chance.
"It's not about Erling or any other player. Until you retire, you can be better."
City's quest for another treble has taken its toll with key midfielder Rodri admitting this week he is in need of a rest.
Guardiola conceded his side have looked jaded in recent weeks after already playing 49 games this season.
The English champions could have a further 13 matches to play if they progress to the finals of the Champions League and FA Cup.
But Guardiola said his options to rotate have been hindered by injuries picked up by defenders John Stones and Kyle Walker on international duty with England last month.
"Take a look at our games and you realise. It is simple. He (Rodri) is so important for the quality he gives us. But if you have a player that doesn't want to play, he won't play," added Guardiola.
"I need to rest the centre-halves also but in friendly games, (Stones and Walker) got injured so they get cannot rest. We are in big, big trouble.
"I had the feeling we were tired in the last games. We will decide tomorrow what we have to do."
One key player coming back from injury is goalkeeper Ederson.
The Brazilian has missed the last five games due to a thigh problem, but was left on the bench against Madrid in midweek, leading to questions over whether Stefan Ortega was Guardiola's new number one.
"Eddie is the first choice," said Guardiola.
"He was ready to play against Madrid. He is ready for tomorrow and we will make the decision."