Jermaine believes the cutting incident was an overreaction to being told she couldn't go to a concert, the TMZ reported.
Paris was hospitalized last month for slicing her arm with a meat cleaver after being barred from attending the concert of shock rocker Marilyn Manson.
"(Paris) has to learn there are certain guidelines when you grow up being a teenager... There are rules," Jermaine said.
The singer seemed to have issues with the guardianship of his late brother's children but he stopped short of naming anyone.
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Jackson's nephew TJ and mother Katherine currently have the joint guardianship of his three children.
The relationship between Paris and her uncles and aunt Janet had soured last year over the dramatic disappearance of Katherine.
Janet, Jermaine, Tito, Randy and Rebbie had united to contest Jackson's will last year, which left his fortune to his mother and three children. Paris was vocal against the family members.