It found that about 60 percent of those surveyed from the 33 nations agreed that the March 2003 invasion of Iraq had increased the likelihood of terrorist attacks.
Just 12 percent believing that the terrorism threat had decreased while a further 15 percent thought it had no effect.
The poll also claimed there was overall support in 20 countries for US forces to withdraw in the next few months.
But 21 of the 34 countries appeared in favour of troops staying in the region until stability is achieved, if the new Iraqi government requested it.
The survey involved 41,856 people by Canadian pollsters GlobeScan and the US Program on International Policy Attitudes (PIPA).
PIPA director Steven Kull said: "All around the world most people view it as having increased the likelihood of terrorist attacks", despite the US administration framing the intervention in Iraq as a means of fighting terrorism.
"The near unanimity of this assessment among countries is remarkable in public opinion polling," Mr Kull said.
Other responses suggested that 21 countries thought the removal of former Iraqi president Saddam Hussein was a mistake; overall, 45 percent were against removing him from power while 36 percent supported the action.
Greatest criticism of the move came from Argentina (74 percent), with strong opposition from Spain (65 percent) and Germany (61 percent).
In Britain, whose government backed the US-led campaign and still has about 8,000 troops in southern Iraq, 40 percent thought removing Saddam was a mistake; in the United States, the figure was 32 percent and in Iraq, 23 percent.
Strongest support for toppling Saddam came from Iraqi respondents (74 percent), Brazil and Poland (65 percent), the United States (60 percent) and Britain (49 percent).
At 85 percent China topped the list those questioned that thought the terrorist threat had risen since the war, followed by South Korea (84 percent) and Egypt (83 percent).
The countries polled were: Afghanistan; Argentina; Australia; Brazil;
Britain; Canada; Chile; China; Democratic Republic of Congo; Egypt; Finland; France; Germany; Ghana; India; Indonesia; Iran; Iraq; Italy; Kenya; Mexico; Nigeria; Philippines; Poland; Russia; Saudi Arabia; Senegal; South Africa; South Korea; Spain; Sri Lanka; Tanzania; Turkey; the United States; and Zimbabwe.