The organisers of a protest against an international "neomasculine" organisation say they have not instructed members to bring pocket knives to protect themselves.

Melbourne feminist groups plan to protest in Federation Square on Saturday night against the all-male group Return of Kings.

The feminist group Mad F---ing Witches is leading the protest against Return of Kings, whose founder Daryush "Roosh" Valizadeh has most recently advocated for rape to be legalised on private property.

"We will hold a peaceful event to gather and dress as witches and cast spells on them and their supporters so they'll be gone from Australia without achieving any of their sorcery," Mad F---ing Witches said in a message to supporters.