Karzai met with British and Pakistani leaders in London for a trilateral summit on regional affairs. British troops are involved in NATO-led operations in Afghanistan, which are set to wind down by 2014.
Their meeting follows an uptick in violence in Afghanistan in recent weeks. The Taliban took responsibility for attacks on a military base belonging to Afghan forces in the Washir district of Helmand province last Wednesday. Hanifa Safi, a provincial director of women's affairs, was killed during an earlier attack in Laghman province.
Nevertheless, British, Pakistani and Afghan leaders said transformation was moving along at a satisfactory pace. A statement added that an "independent, peaceful, self-reliant and democratic Afghanistan was necessary" for regional stability.
Pakistan has expressed frustration about cross-border attacks by international forces operating in Afghanistan. Karzai said a political solution was needed in Afghanistan to end the ongoing violence.
Lasting peace would come "through an inclusive and dignified process, involving the Taliban, Hezb-e-Islami and other armed opposition groups," Karzai said, according to London's readout of the meeting.