Pakistanis from religious and hard-line groups have rallied in the capital, Islamabad, in the latest in a string of demonstrations highlighting tensions in the nuclear-armed state.
Protesters chanted, "Death to America," as hundreds of riot police stood guard.
The protest was organized by the Defense of Pakistan, a coalition of around 40 mostly extremist parties.
Police said some 2,500 attended the demonstration as it got under way, but witnesses estimated the crowd at 3,500.
Several extremist leaders linked to the coalition were prevented by the authorities from attending.
One cleric, Maulana Sami ul-Haq, told AFP that the demonstrators intended to “protest against U.S. intervention in Pakistan” and “the possible resumption of NATO supplies.”
Defense of Pakistan was set up after U.S. air strikes killed 24 Pakistani soldiers on the Afghan border in November, which saw Pakistan shut the border to NATO supplies.
Some observers suggest that supporters of Pakistan's military might be behind recent protests in an effort to gird the security establishment as it competes for influence and power with the country's civilian leadership.
Compiled from agency and media reports