Instead, the Taliban chief, who has a $10 million US bounty on his head, has repeated his threat to prosecute Karzai in an Islamic court for the "massacre" of Afghans, the spokesperson said on Saturday.
"The infidels of the entire world have gathered in Afghanistan, occupied it and taken the Afghans hostage," Tayyab Agha, the spokesperson, said by satellite phone.
"There can be no talks with the Afghan puppet government in the presence of foreign occupying forces. Hamid Karzai and his colleagues should first free themselves from the slavery of foreign infidels and then invite us for negotiations."
Karzai on Friday repeated his offer for talks if the Taliban leadership met several conditions, including ending support from elements in Pakistan and the involvement of foreign fighters.
"The Taliban will not negotiate in the presence of foreign forces and will continue their armed jihad under Mullah Omar's leadership until the ouster of foreign forces," Agha said.
General James Jones, Nato's supreme commander for Europe, said the force still did not have enough troops and appealed for countries to allow more flexibility in deployment.
Nato has appealed to member
states to send more troops
He also said that early indications were that movement by Taliban fighters across the border with Pakistan had increased, despite recent agreements aimed at halting such crossings.
Some Nato countries, such as Germany, have been criticised for keeping the bulk of their troops in the relatively safe north when most of the fighting is in the south.
"Caveats are a fact of life, but I believe there is room for improvement in this force," Jones told reporters at the main US base in Bagram.
Jones's three-day visit comes as Nato finds itself under fire for killing what witnesses say were 60 civilians in an aerial bombing this week and pictures showing German soldiers desecrating human skulls and other remains in Kabul.
Jones said he had personally apologised to Karzai, saying the bombing occurred in "the fog and heat of war" and blaming the Taliban for using villagers as human shields.
Nato has confirmed several civilian deaths, but not put a number on the toll.