The incident had taken place when the guardian minister Girish Mahajan was confronted by protesters at the District Collector's office here on the issue of release of water for Marathwada from the Gangapur dam.
Reporter Mahindra Mahajan, who works with a Marathi daily, was allegedly beaten up by the deputy commissioner of police Avinash Bargal.
Mahajan was hospitalised later.
Jagannathan assured that action would be taken against the officer if he was found to be guilty.