The Mumbai police on Thursday served a notice to Maharashtra Navnirman Sena chief Raj Thackeray, 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 in Mumbai.

The notice says that 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 in the evening.

"In his political activities, he must not commit any cognisable crime, that is what the notice says. This is basically a preventive notice," said the officer.

The notice has been served under the provisions of 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 his 70-minute speech, in which he attacked North Indians.

Raj, who led a violent anti-North Indian campaign in February, was arrested on the same charge on February 13 before being released on bail.