Fighting in Afghanistan has been the worst this year since the Taliban's overthrow in 2001, with about 4,000 people killed, a quarter of them civilians.
"Pakistan still hasn't given up the hope of making us slaves. But they cannot," Karzai said in a speech at a boys' high school in the southern city of Kandahar, the birthplace of the Taliban.
"This tyranny against our people is not by the nation of Pakistan, it is by the government of Pakistan."
Karzai, who on Tuesday for the first time publicly accused the Pakistani government of encouraging attacks inside Afghanistan, linked a recent spate of suicide bombs to a visit by Khurshid Kasuri, the Pakistani foreign minister.
|"This tyranny against our people is not by the nation of Pakistan, it is by the government of Pakistan"|
"Before his arrival they wanted to scare me off, they wanted me to surrender. But I'm not scared," Karzai said. "They wanted to make me accept to become their slave. But even if they kill 25 million people [in Afghanistan] I won't become their slave."
Pakistan fostered the Taliban during the 1990s but officially dropped support for the movement after the September 11 attacks on the United States.
Pakistan has said it is "doing whatever is needed" to prevent its territory being used for Taliban activities.
Tasnim Aslam, a Pakistani foreign ministry spokeswoman, said: "The problem of Afghanistan is primarily inside Afghanistan and it should be resolved there. The Taliban are operating well inside Afghanistan."
Both countries are planning tribal councils in an attempt to stop the violence. But no date or venue has been set for the meetings, which Karzai and his Pakistani counterpart, Pervez Musharraf, would also take part in.
On Monday, the Taliban suggested that they were unlikely to join the councils while 40,000 foreign troops remain in the country under either Nato or US command.
Relations between the two neighbours have frequently been strained since Pakistan was created in 1947, often due to border disagreements.
The Taliban, most of them from Afghanistan's ethnic Pashtun majority, typically have tribal links on both sides of the border.
Anis said Islamabad wanted a weak government in Afghanistan that would not raise the issue of the "Durand Line", the Afghan/Pakistan border drawn up by the British.
The border was drawn up so that it cut through tribal areas occupied by Pashtuns. About 28 million Pashtuns are found on the Pakistan side of the line and around half that number on the Afghan side.