Haaland scored on a header and remarkable bicycle kick, taking his tally to 44 goals in all competitions this season, with 30 of those coming in the Premier League.
His total is now tied for the most ever by a Premier League player in all competitions in a single campaign, equalling Ruud van Nistelrooy in 2002-03 and Mohamed Salah in 2017-18.
"We have lived two incredible decades with Cristiano Ronaldo and Lionel Messi, but he is on that level," Guardiola told the BBC on Saturday.
Guardiola was in awe of Haaland's execution of his second goal, which he acrobatically volleyed home off a cross from Jack Grealish.
"It is not easy to pick the ball up in the sky and put it on the grass," Guardiola said. "You can't imagine at his height he has this ability. Exceptional goal."
Haaland, who joined City from Borussia Dortmund, is now four short of the record of 34 goals in a Premier League season set by Alan Shearer and Andy Cole.
City are second in the league with 67 points after 29 games, five behind leaders Arsenal.
