The White House says President Barack Obama considers the death of 24 Pakistani troops in a cross-border fight involving NATO forces "a tragedy."
The air strikes on November 26 at two remote border posts in the Mohmand tribal area near the Afghan border have enraged Pakistan.
On November 28, White House spokesman Jay Carney intimated that Washington was taking the matter "very seriously."
"It is very much in America's national security interest to maintain a cooperative relationship with Pakistan because we have shared interests in the fight against terrorism," he said. "And so we will continue to work on that relationship."
Earlier on November 28, Pakistan denied reports blaming Pakistani troops
for triggering the air strikes, with the country's chief army spokesman saying NATO and Afghanistan were "trying to wriggle out of the situation by making excuses."
Major General Athar Abbas said the strikes lasted almost two hours and continued even after local commanders had asked NATO to stop the attacks.
NATO has apologized for what it called a "tragic unintended incident."
NATO and the U.S. Central Command have promised separate inquiries into the event.
compiled from agency reports