While many in Pakistan hailed the killing of terror chief Osama Bin Laden, some condemned the operation by US special forces.
In the city of Quetta in the lawless southwestern province of Baluchistan, hundreds of demonstrators assembled on the streets to honor Osama and to demand vengeance against the US, according to a report from Agence France Presse.
The protest was organized by Jamiat Ulema-e-Islam, a religious party in Quetta.
They also chanted slogans in praise of the Taliban and its chief Mullah Omar.
Federal politician Maulawi Asmatullah participated in the anti-American rally.
Bin Laden was the hero of the Muslim world and after his martyrdom he has won the title of great mujahed [Muslim fighter], Asmatullah said.
His martyrdom will not end the movement. It will continue and thousands more bin Ladens will be born. Today's operation shows the US has no respect for international borders and they can violate international laws any time, he added.
Organizers claimed that between 1,000 and 1,200 attended the event.
Protesters reportedly burned American flags in the demonstration before dispersing peacefully.
Already, the Pakistani Taliban has warned government officials it will take revenge.
Ehsanullah Ehsan, a spokesman for Tehrik-e-Taliban Pakistan (TTP) told Reuters: Now Pakistani rulers, President [Asif] Zardari and the army will be our first targets. America will be our second target.
Baluchistan, which borders Iran and Afghanistan, is a remote [art of Pakistan which has itself been involved in an insurgency by local Baluch tribes seeking increased autonomy from Islamabad.
The Taliban has engineered many attacks in the region as well.