The unnamed woman, reports The Sun, accused Haaland of leaving her with "suspected whiplash and concussion", taking her complaint to the club and also local police.
Filling in as City mascot, Moonbeam, the woman alleges she received knocks to her head from Haaland as they posed ahead of the win against Southampton in October.
After her complaint, an investigation concluded that Haaland did not cause her injuries. A report stated: "Erling Haaland always does a gentle touch on the back or head of Moonbeam as recognition."
The woman had been working at the City ticket office since June, though was let go in December.
A Manchester City spokesperson said: "We fully investigated and found that none of the evidence, including video footage, backed up the claim that an injury was sustained in the manner alleged.
"We’re also aware a complaint was made to Greater Manchester Police and no further action was taken by them either."