Many of the protesters were carrying banners carrying slogans condemning the role of the United States in Pakistan.
"This is a great point of contention for many Pakistanis, not just the supporters of the political party gathered here," Hanna said.
"The speakers are basing part of their criticism on their belief that Pakistan is doing ... the work of the United States in its so-called 'war on terror'."
Washington has declared its support for the military operation in the NWFP, after criticising a peace deal signed by Islamanbad and pro-Taliban groups in the region in February.
The US sees the area as vital to its efforts to combat a resurgent Taliban across the border in Afghanistan.
Qazi Hussein Ahmed, the leader Jamaat-e-Islami, told Al Jazeera that the military offensive was directed at the "innocent people of Malakand division".
"They have targeted the population by bombardment from the air and use of artillery .. they will hit the population, their villages, their towns and a fear has been created among the people," he said.
Ahmed said that the military's actions would lead to an increase in pro-Taliban violence.
"[The government] should consult the people of the area, they have traditional ways of containing the militancy, they have got traditional ways of consulting each other. These people can contain all the people who are creating chaos within their society."
Another protest was reported in Karachi, the capital of southern Sindh province.
Pakistani security forces said they had seized several key areas in Mingora inside the Swat valley on Sunday.
Military officials said troops were in control of several main intersections and three main squares after heavy urban clashes, the military said.
Pakistani troops entered the town a day earlier, engaging in street battles with the Taliban and killing at least 17 fighters, Major-General Athar Abbas, a military spokesman, said.
"We have blocked all the entries and exits," he told Al Jazeera.
"Now the forces that were already present inside have linked up with the outside forces, and with this increased ratio they are moving from one end to the other.
"It will take more time."
Mingora, the administrative and business hub of Swat in the NWFP, has been under the effective control of Taliban fighters for weeks.
Many of the 300,000 people who live in Mingora are believed to have fled since the military began its offensive in Swat, Lower Dir and Buner districts of the NWFP several weeks ago.
However, the military says that between 10,000 and 20,000 civilians remain trapped in Mingora, with dwindling supplies of food and no access to medical care.
The military also sent helicopter gunships and ground troops to launch an attack in the nearby tribal area of Orakzai on Sunday.
"Troops backed by attack helicopters retaliated, killing eight militants," a security official told the AFP news agency.
Mohammad Yasin, a local government official, told The Associated Press news agency that the military had targeted strongholds of Hakeemullah Mehsud, a Pakistani Taliban leader.
Hundreds of people have fled the area amid the fighting, he said.
The military has said that about 1,100 suspected Taliban fighters have died so far in the offensive, but is still to give a total of civilian casualties.
Residents fleeing the region have reported dozens of ordinary Pakistanis killed in the fighting.