"We will turn the tide against HIV/Aids once and for all," he said, adding that he would visit Africa during 2008.
He spoke as millions of people around the world prepared for World Aids Day.
A special concert is being held in South Africa backed by former president Nelson Mandela - a prominent campaigner in the fight against the disease.
More than five million South Africans are HIV positive.
See a breakdown of global HIV prevalence
However, recent reports suggest that like most countries in the region, adult HIV prevalence is either stable or has started to decline.
After years in which the South African government was accused of "Aids denialism", the country now has the world's largest programme of antiretroviral (ARV) treatment.
But HIV/Aids campaigners say more must still be done - especially in preventing mother-to-child HIV transmission.
The United Nations recently reduced its estimate of the number of people living with HIV/Aids to 33 million from nearly 40 million after re-evaluating its data collection methods.
Marking World Aids Day in New York, Secretary General Ban Ki-moon attended a midnight church ceremony and called for a move towards universal access to HIV prevention and treatment.
"Aids is a disease unlike any other. Aids is a social issue, a human rights issue, an economic issue. It targets young adults just as they should be contributing economic development, intellectual growth, and bringing up their children."
Almost three-quarters of Aids-related deaths during 2006 were in sub-Saharan Africa. Two-thirds of those living with HIV are found there.
The number of people living with the virus has increased everywhere, with the most striking increases in East Asia and Central Asia/Eastern Europe.
The BBC's David Loyn, in Afghanistan, says that nearly 30 years after HIV/Aids first emerged onto the world stage, it is now moving into the country with unpredictable consequences.
Only 266 cases of HIV/Aids have been recorded in Afghanistan but returning refugees, truck drivers, and Afghans now flying abroad to work are bringing in the disease.
There are fears the official figures are just the tip of the iceberg, our correspondent says.