The demonstrators, holding sticks, pelted stones at the riot police and other security personnel and tried to move forward.
They also burnt the entry gate of the Public Secretariat, which houses ministers' offices and occupied the main road leading to the secretariat. Several other important buildings, including the state TV, are also located in the same area.
The clashes started as government employees started coming to offices in the morning which hampered the activities of the people. The police were forced to close gates of ministers' offices.
Supporters of religious leader, Tahir ul Qadri, are trying to stage sit-in outside the Prime Minister's house; however, the security forces have foiled their attempt.
The security forces have also frustrated attempts by leader of Pakistan Tehrik-e-Insaf, Imran Khan, who also wanted to march towards the PM house.
Tahir ul Qadri and Imran Khan had been demanding resignation of Prime Minister Nawaz Sharif since they have started anti-gov't protest on August 14.
The police started shelling on the marchers just meters away from the PM's house, witnesses said.
Prime Minister Nawaz Sharif has rejected the demand but offered talks to the two opposition leaders to politically resolve the political impasse.