"A vehicle accompanying Anna's car, carrying books and other material for his ongoing Maharashtra tour has been attacked; windows broken. Annaji is safe," tweeted Team Anna member Kiran Bedi.
Hazare is on a five-week Maharashtra tour.
Hazare's assistant Suresh Pathare said a group of people first threw stones and then shouted slogans in support of Rahul Gandhi and Sonia Gandhi.
Anna Hazare (File photo)
"However, the attack was on the vehicle that we used for sale of books. Nobody is hurt. Anna and other crew are safe. Do not worry," he said.
Nagpur police, however, denied any information about the incident.
Earlier in the day, Hazare's convoy was shown black flags at some places.
Hazare began his Maharashtra tour from Shirdi May 1 to create awareness on the need for a strong Lokayukta legislation in the state. His tour will end June 6.