Prime Minister Shaukat Aziz, meanwhile, condemned the strike that killed at least 17 people in a village near the Afghan border, but he said he would go ahead with a planned trip Tuesday to the United States to build business ties.
Thousands of Pakistanis poured into streets in cities across the country on Saturday and Sunday chanting "Death to America" and demanding U.S. troops leave neighboring Afghanistan. No protests were reported Monday, but Islamic groups promised more rallies later this week.
"There will be more ... bigger protests," said Shahid Shamsi, spokesman for an alliance of Islamic groups.
"Pakistani civilians, including children, were killed," he said. "Principles cannot be broken in the name of (fighting) terrorism."
Protesters believe Friday's attack was the work of U.S. forces in Afghanistan. Washington has 20,000 soldiers in that country searching for Taliban and al Qaeda fighters, but Pakistan says it has not given the Americans permission to pursue their enemies across the border, but CBS News correspondent David Martin reports administration officials say the operation was approved in advance by President Perez Musharraf's government.
"They should try to work to improve their image," Information Minister Sheikh Rashid Ahmed said of U.S. activities in the region. He said the attack "also created problems for this government," including protests from allied parties within the ruling coalition.
The prime minister said he is still scheduled to leave Tuesday for the United States, where he will talk about security issues and meet business leaders to encourage foreign investment.
Aziz called the airstrike "very regrettable." But, he added, "I don't think that takes away from the fact that Pakistan needs investment."
Pakistani officials have strongly condemned the strike, without directly blaming the United States. The United States hasn't confirmed involvement in the attack but Secretary of State Condoleezza Rice said al Qaeda can't be treated "lightly."
She praised the Pakistanis as "great allies" in the war against terrorism but said extremists continue to occupy parts of Pakistan, noting that two attempts have been made on the life of President Gen. Pervez Musharraf.