"The police resorted to using a mild force when the crowd, instead of vacating the highway, started pelting stones," Superintendent of Police (city) Shravan Kumar Singh said.
He said two police teams have been formed to trace the girl, studying in Class XI.
Singh said, the 17-year-old girl, daughter of retired army personnel Pradeep Kumar, had left her home last morning for Raman Lal Shorawala School.
The local residents blocked the highway alleging the police's "failure" to trace the girl even 24 hours after her kidnapping.