A foot injury has kept 23-year-old Haaland out since the defeat by Aston Villa on 6 December, although few details have been given.
It had been hoped City’s top scorer would return for the Club World Cup in December but the injury has still not healed.
“It’s the bone. It needs time,” Guardiola said.
“With every injury you can do whatever you want but it’s a question of time.”
Norway international Haaland, who has scored 19 goals in 22 club games this season, had already been ruled out of Saturday’s Premier League match against Newcastle, after which City have a 13-day break, when they will depart for warm weather training in Abu Dhabi.
If he misses the remainder of the month he will be absent for the visit to Tottenham in the FA Cup on 26 January and the league match at home against Burnley on 31 January.
“It’s fine but the doctors decided to stop for one week and maybe restart in Abu Dhabi,” Guardiola said.
“Hopefully at the end of this month he’ll be ready. It was a little bit more than we expected in the beginning.”
City are unbeaten in the eight games Haaland has missed, including their Club World Cup victory, and sit five points off Premier League leaders Liverpool with a game in hand.
But Guardiola said his side miss Haaland “a lot”.
“We need him,” Guardiola said. “Hopefully he can come back and play the last four or five months without a problem.”
Centre-back Manuel Akanji is likely to miss a similar period after he was forced off in the 18th minute of last week’s FA Cup win against Huddersfield.
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