Washington: The United States has appealed to all sides in Pakistan to refrain from violence and resolve their differences through peaceful discussions in a way that strengthens democracy in the country.

"We are carefully monitoring the demonstrations in Islamabad. We urge all sides to refrain from violence, exercise restraint, and respect the rule of law," State Department Deputy Spokesperson Marie Harf told reporters at her daily news conference.

"We believe that all parties here should work together to resolve their differences through peaceful dialogue in a way that strengthens Pakistan`s democracy, and that`s certainly the consistent message we have sent," she said in response to a question.

Pakistan`s cricketer turned politician and opposition leader Imran Khan and cleric Tahirul Qadri, who are calling on Prime Minister Nawaz Sharif to resign, tonight marched with thousands of their supporters towards the Parliament.

They entered the heavily fortified `Red Zone`, Islamabad`s diplomatic and political enclave, despite the government`s efforts to keep them away. Minor clashes were also reported to have taken place between anti-government protesters and security personnel.

The agitators led by Khan want Sharif to step down over alleged rigging of last year`s parliamentary elections. Qadri also wants Prime Minister Sharif ousted.