US politicians on Capitol Hill have been divided over the significance of the documents, with some saying they serve as a wake-up call for the US to leave Afghanistan.
But Obama insisted the revelations justify his new military strategy and he urged politicians to approve $37bn in funds for the war effort.
Congress obliged later in the day as the House of Representatives took final action to approve the money - $33bn for the military and $4bn for a related civilian surge - months after the president had requested it.
The tally was 308-114 but most of the "no" votes came from Obama's own Democratic Party.
The documents published by Wikileaks detail allegations that US forces sought to cover up civilian deaths as well as US concern that Pakistan secretly aided Taliban fighters even as it took billions of dollars in US aid.
A collection of field intelligence and threat reports from before Obama ordered an increase of 30,000 troops deployed to Afghanistan, the documents also illustrated the Pentagon's bleak assessment of the war amid deteriorating security and a Taliban resurgence.
Congress however, has backed the war so far, and an early test of that continued support came when the Senate Foreign Relations Committee, led by Democratic Senator John Kerry, opened a hearing on the Afghan war.
At the hearing, few members mentioned the leak of documents but several expressed frustration at the lack of progress in improving Afghan governance and in drawing more ordinary Afghans away from the Taliban.
|Many US politicians are sceptical over the continued war effort in Afghanistan [AFP]
Kerry also questioned why the Taliban, with fewer resources, is able to field fighters who are more committed than Afghan soldiers.
"What's going on here?'' Kerry asked.
In his only reference to the leak, Kerry called the material "overhyped,'' and said that it was released in violation of federal law.
Kit Bond, a Republican senator on the Senate Intelligence Committee, said on Tuesday that he was worried that the leaks would not stop "until we see someone in an orange jump suit,'' the uniform of many people in US prisons.
The army meanwhile is leading the Pentagon's inquiry into the source of the leak.
A federal law enforcement official told the Associated Press that the Justice Department was also helping in the investigation.
The US military's criminal investigative division previously led an investigation into Bradley Manning, an army intelligence specialist charged with leaking other material to Wikileaks.