Delegates at a Nato-sponsored conference in Rome have been considering ways of strengthening Afghanistan's justice system.
President Karzai has been discussing ways to shore up the justice system
Despite progress in education, health care and the economy, the legal system still faces huge challenges.
There are only 200 lawyers, violent crime goes unpunished and the police are poorly trained.
The BBC correspondent in Rome says that success can only be achieved with the support of the Afghan people.
This is undermined when civilians are killed in Nato or US-led operations.
The alliance must do everything it can to avoid causing civilian casualties in the country, its Secretary-General, Jaap de Hoop Scheffer, said.
"Our opponents mingle and mix with innocent civilians," he was quoted as saying by the Associated Press news agency.
"We do not intentionally kill; they behead people, they burn schools, they kill women and children."
UN Secretary-General Ban Ki-moon said he was "very much saddened and troubled" by the deaths of civilians in Afghanistan.
"We simply cannot hide from the reality that civilian casualties, no matter how accidental, strengthen our enemies and undermine our efforts," he said.
President Karzai recently accused foreign forces of "reckless" attacks in Afghanistan.
He has ordered a more thorough investigation into air raids in Helmand province last week.
Afghan sources say a total of 45 civilians and 62 Taleban fighters died in Friday's strike but US-led coalition forces and Nato question the figure.
Last week Mr Karzai said the foreign forces were killing civilians with an "extreme use of force" and were not co-ordinating properly with the Afghan government.
Nato forces say they welcome the investigation.