Prosecution for certain offences against this Act to be in the discretion of police

lt shall not, except in obedience to a rule, regulation or order made by Government or by the Commissioner, be incumbent on the police to prosecute for an offence punishable under Section 84, Section 91, sub-section (1) Section 99, Section 100 or Section 105 when such offence has not occasioned serious mischief and has been promptly desisted from on a warming being given.