Karzai met representatives of eight governments, including Abdullah Gul, the Turkish president and Mahmoud Ahmadinejad, the Iranian president, on the sidelines of an economic summit held by the Organisation of the Islamic Conference (OIC) in Istanbul.
Most trade with landlocked Afghanistan passes through the conflict-ridden border with Pakistan and through Iran.
Karzai said: "Afghanistan's interest is primarily in having close brotherly relations with its neighbours, freedom of trade and transit, and an effective environment of co-operation."
A Turkish foreign ministry official said there would be a follow-up conference on Afghanistan in the near future, which Turkey had offered to host.
"As stakeholders in the region, we cannot expect that the United States and other Western powers solve the problems by themselves. We should shoulder our responsibilities," Gul said.
The widespread fraud reported during the Afghan election and the refusal of Karzai's chief rival to contest a run-off have damaged Karzai's credibility at the start of his second term.
Karzai was seen as a guarantor of Western aid when he was first elected in 2004, but his relations with the US and other Western allies have become strained by allegations of corruption and poor governance.
His popularity has dwindled as many ordinary Afghans believe they have not benefited from billions of dollars in aid.
Also speaking at the summit, Ahmadinejad said the global economic order needs "radical change", calling for Islamic principles to replace capitalist values.
"The present economic crisis is due to the capitalist system. The world needs radical change," the Iranian president said.
Describing interest rates as the "biggest and most fundamental problem of the capitalist system," Ahmadinejad said economic programmes based on Islamic principles offered the way out.
"The world is looking for fairer values that we cannot find in the capitalist system. The world system based on usury has collapsed, proving its failure," he said.
"We have to draw up programmes based on Islamic economic thinkers. That way we can guide people to happiness, security, justice and honesty. This is the most correct way to salvation."
The president urged member countries of the OIC to agree to carrying out trade in their national currencies and setting up a common market.
"By announcing the type of money to be used between member countries, we will be saved from the adverse effects of global capitalism," he said.
Source: Al Jazeera (English)