The organization's index, released Tuesday, indicated the world has become 5 percent less peaceful since 2008.
The three most peaceful countries are Iceland, Denmark and New Zealand, and Europe was the most peaceful region, Vision of Humanity, based in New York, said.
A newly elected government and a steady recovery from the 2011 turmoil helped Libya improve the most in its peace score since last year, the organization said.
The three least peaceful countries are Afghanistan, Somalia and Syria. Syria's score fell by 70 percent since 2008.
Since the 2008, 110 countries have become less peaceful, while 48 have improved their score, the organization said, attributing three reasons for the deterioration from last year -- the number of homicides, military expenditure as a percentage of a gross domestic product and political instability.
Vision of Humanity said the total economic impact of containing violence is equivalent to 11 percent off the global GDP, or $9.46 trillion.
The organization said if the world reduced the cost of violence by 50 percent, enough money would be generated to repay the debt of the developing world, provide enough money for the European stability mechanism and fund the additional amount needed to fund the United Nations' Millennium Development Goals.