The warning has been issued by sub divisional magistrate R D Ram on a complaint by Congress leader Munna Singh that Vishwas was violating section 144 and using national flag during his campaign.
The SDM said the AAP leader has been warned and if another complaint was received, strict action would be taken.
Meanwhile, the district administration has banned a 'kavi sammelan' to be organised at Ramganj in which Vishwas was to be the chief guest.
The AAP leader alleged that the event, though organised by traders, has been "banned at Congress' behest".
A defiant Vishwas said he would attend the sammelan and was ready to even go to jail.