Officials say at least three people were killed and hundreds injured in clashes between police and protesters in the capital, Islamabad.
Police fired tear gas and rubber bullets at protesters trying to storm the residence of Prime Minister Nawaz Sharif on August 30.
The violence continued on August 31.
Radio Mashaal says police were among the wounded.
Islamabad police chief Khalid Khattak said the protesters were armed with big hammers, wire cutters and axes, and a crane.
Defense Minister Khwaja Mohammad Asif said police later managed to clear most of the protesters from the parliament building's parking area and lawns.
Protests demanding Sharif's resignation were also taking place in Lahore, Karachi and other Pakistani cities, according to TV reports.
In Islamabad, thousands of protesters had marched from parliament where they have been camped out for days now, demanding Sharif step down.
The demonstrators claim Sharif won elections in 2013 due to massive voter fraud.
On August 30, Sharif, who has the backing of parliament and many political parties, once again said he will not go.
The demonstration began with a march in the eastern city of Lahore on August 14, Pakistan's Independence Day.
Protest leaders Imran Khan and Tahir ul-Qadri have called for millions of protesters to join but crowds have remained in the thousands and mostly peaceful up till August 30.
Khan, a cricket-legend-turned politician, described the police action against the crowd in Islamabad as illegal.
"Now we will show this government, we will call for countrywide agitation and we will jam the whole of Pakistan," Khan said.
Sharif's spokesman Asif Kirmani said the government had to use force after protesters tried to attack the center of state power in the capital.
It was not clear whether Sharif was at the residence on August 30.
"A state can't be left at the mercy of some thousand people," Kirmani said in an interview with Geo News TV.
Based on reporting by Radio Mashaal, AP, AFP, dpa, Dawn, Geo TV and Reuters