One of the members who attended at the meeting, the mufti of the northern Perak state, Harussani Idris Zakaria, slammed such behaviour saying it showed little respect for the faith.
Harussani, who chaired the meeting, noted that the behaviour and dress of this growing number of “disrespectful” young women can turn some of them to homosexuality.
Whilst not explicitly banned in Malaysia, homosexuality is effectively illegal under a law that prohibits sex acts “against the order of nature.”
“It doesn't matter if it's a law or not. When it's wrong, it's wrong. It is a sin,” Harussani told said. “Tomboy (behaviour) is forbidden in Islam.”
Under the fatwa girls cannot sport short hair and dress, walk and act like boys, Harussani said. Boys too must respect social norms.
For Harussani everyone has a duty to respect God and act according to nature.
The tomboy fatwa comes after recent cases in which scenes of young women bullying and carousing showed up online.
A well-known Malaysian Muslim actress caused uproar last year when she shaved her head bald for a film.
At the time Harussani and other muftis urged Muslims not to watch the movie, harshly chastising the actress for violating Islam by making herself look like a man.
Muslims make up some 60 percent of Malaysia's 27 million people, and are subject to Islamic laws and the council's edicts, even if the rulings have not been enshrined in national or Sharia law.
It was not immediately clear what kind of punishment awaited those who violate the tomboy fatwa, unless the edict is incorporated into national or Sharia law.