It is unlawful and constitutes incitement to riot for a person or persons, intending to cause or to aid or abet the institution or maintenance of a riot, to do an act or engage in conduct that urges other persons to commit acts of unlawful force or violence, or the unlawful burning or destroying of property, or the unlawful interference with a police officer, peace officer, fireman or a member of the Michigan national guard or any unit of the armed services officially assigned to riot duty in the lawful performance of his duty.