The Norwegian striker, who has scored 11 Premier League goals this season, was taken off at half-time in their 6-1 win over the Cherries.
Haaland appeared to be hobbling as he made his way off the pitch with fans concerned over his fitness.
However, Guardiola has now revealed why he took him off and hinted that his absence could just be a matter of days.
Speaking to BBC Sport after the win, the City boss said: "He twisted the ankle. Hopefully not a big issue.
"We'll see in the next hours and days," Guardiola added, before confirming he is unsure whether Haaland will be fit for their next game.
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City don't have long to wait until they return to action as they host Young Boys in the Champions League on Tuesday night.
They then make the trip to face Chelsea five days later as they look to exert their dominance at the top of the Premier League, but Guardiola suggested he could be fit again in time for the weekend.
Haaland was unusually quiet in the first-half against Bournemouth as he failed to score or assist despite City netting three goals.
Jeremy Doku was outstanding on the afternoon and opened the scoring on the half-hour mark.
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He then assisted Bernardo Silva for the second and turned provider again for the third as his shot went in off Manuel Akanji.
Haaland did not feature in the second-half and was replaced by Phil Foden who netted after yet another assist from Doku.
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Bournemouth reduced the deficit by one goal when Luis Sinisterra found the target approaching the final 15 minutes.
City were not done there though as Silva scored his second of the day and Nathan Ake completed the scoring in the closing stages.