Afghanistan who have helped us at risk and because our adversaries can learn a lot abut our technics and tactics," Gates said in the ABC programme This Week on Sunday.
Gates noted that it was up to the Justice Department to see whether criminal proceedings would be instituted against WikiLeaks but the organisation was morally guilty for putting people's lives at risk.
"There's also a moral culpability, and that's where I think WikiLeaks is guilty," he said, adding "They have put this out without any regard whatsoever for the consequences."
Last week, the Taliban issued a statement that it was going through the leaked documents and it would hunt down the informants.
Over 90,000 documents leaked on last Sunday map the US war in Afghanistan from 2004 to 2009. The documents includes plans of US operations, threat reports from intelligence sources, descriptions of meeting between politicians, military officials and insurgents and plans hatched by the militants.
The founder of the website, Julian Assange, a 39-year-old Australian, has said an additional 15,000 documents would also be revealed after names of individuals in the reports could be redacted.
Washington immediately condemned the leak.
Following the backlash against the leak from some groups, Assange defended his decision on grounds that it informed the public about the realities behind the nine-year old war.
In a video aired by CNN, last week, Assange said that he was "disappointed in what was left out" of Defense Secretary Robert Gates' comment.
"Secretary Gates spoke about hypothetical blood but the grounds of Iraq and Afghanistan are covered with real blood," Assange said.
"Secretary Gates has overseen the killing of thousands of children and adults in Iraq and Afghanistan," he added, noting that Gates should have announced criminal investigations and a broad inquiry into the allegations that stem from the report.
The documents suggest that intelligence agencies in Pakistan and Iran maybe fueling the insurgency in Afghanistan, coalition forces have targeted civilians in hundreds of
incidents and US has a special force that hunts down Taliban leaders for "kill or capture" without trial.
A lot information in WikiLeaks is not completely new but it is still being viewed as the largest intelligence leak in history that may impact US President Barack Obama's strategies in Afghanistan—especially because the information underlines how badly the war is going for the US.
But Washington insists that the leak has and will potentially cause more damage.
"Mr Assange can say whatever he likes about the greater good he thinks he and his source are doing, but the truth is they might already have on their hands the blood of some young soldier or that of an Afghan family," Mike Mullen, chairman of the Joint Chiefs of Staff, said last week.
Meanwhile, the soldier being blamed for the leak, 22-year-old Private Bradley Manning has been moved from a detention facility in Kuwait to a military installation in Virginia.
Manning was originally arrested in April for leaking another video called "Collateral Murder" made in 2007, which was published by WikiLeaks. It showed American soldiers firing on a group that contained Iraqi children and journalists.
In an incident related to the investigation into the source of the leaks, a Seattle-based software developer who has volunteered for WikiLeaks said he was detained at Newark
Liberty International Airport on Thursday and questioned for three hours, the New York Times reported.
The developer, Jacob Appelbaum, 27, said Sunday that he was returning from an overseas trip when agents from Immigration and Customs Enforcement and from the Army's criminal investigation division asked him about Assange and also seized his laptop computer and three cellphones.
Only the laptop was returned, according to NYT.
Appelbaum said he was not involved with WikiLeaks and that he never communicated with Private Manning
"They questioned my ability to re-enter the US even though I'm a US citizen," he said in a telephone interview from Las Vegas."