According to police, the pro-Telangana activists, among scores of students attacked Ranga Reddy's car, demanding that he should resign in support of separate Telangana state.
The CPM is opposed to the division of Andhra Pradesh.
The slogan shouting protesters pelted stones on the MLA's car, in which he was travelling, damaging its windowpanes.
However, police immediately dispersed the agitationists by resorting to lathi-charge, a senior police official was quoted by news agency as saying.
The MLA was safely moved away from the place and he did not receive any injuries.
Six pro-Telangana protesters were also taken into preventive custody and the situation is normal, the police official added.