Speaking in Kabul, Karzai also asked local leaders to use their influence to try to end opium-poppy farming.
Meanwhile, the United States said it will double efforts against Afghanistan's drug output, focusing on both crop eradication and curbing the drug trade.
The comments come after a UN report showed this year's opium-poppy harvest to be Afghanistan's biggest ever.
The report by the UN Office On Drugs and Crime (UNODC) said Afghanistan is now producing nearly 95 percent of the world's opiates.
The UNODC also warned that opiate use in the countries neighboring Afghanistan has grown along with Afghan drug production.
(AP, AFP, Reuters)