The police on Thursday served a notice to MNS chief Raj Thackeray, who targeted north Indians recently, asking him to observe restraint and not to commit any cognisable offence through his speeches and writings which can create law and order problems.Raj, however, refused to accept the notice forcing the police team to paste it outside his Shivaji Park residence here.The notice says a certain section of the society feels insecure in the wake of recent events which can create a law and order situation, said a senior police officer who pasted the notice on Raj’s residence late on Thursday evening.“In his political activities, he must not commit any cognisable crime is what the notice says. This is basically a preventive notice,” said the officer.The notice has been served under Section 149 of the Criminal Procedure Code and can be used against Raj in a court if he commits a cognisable crime, the officer added.The police, who had served a similar notice on Raj before his rally on May 3, are contemplating action against him for promoting enmity between different groups of people during Saturday’s 70-minute speech in which he attacked north Indians.