The White House refused on Thursday to comment directly on Pakistani anger at a cross-border raid by Afghanistan-based international forces just days before Pakistan's presidential vote.
Spokeswoman Dana Perino said US authorities were "working to increase coordination and cooperation and supporting the Pakistanis, as we work to fight against the Taliban in a coordinated way."
But Perino met questions about US policy in general regarding cross-border raids inside Pakistan or details of the Wednesday strike, which Islamabad has denounced as "shameful" and unjustified, with a stone wall.
"In regards to the reports about that incident, we have not commented, and I won't today," she told reporters. "I'm just not going to comment on the incident in any way."
Authorities in Pakistan -- a close US ally in the global war on terrorism -- earlier summoned the US ambassador in protest at the incident in tribal South Waziristan, in which local officials said at least 15 people were killed.
Wednesday's raid marked the first time Pakistan has accused international troops based in Afghanistan of a direct attack on its soil since they were deployed in late 2001 to oust the hardline Taliban regime from power in Kabul.
Both the US-led coalition and the separate NATO-led security force operating in Afghanistan have said they have no knowledge of any such incident in South Waziristan, a known haven for Taliban and Al-Qaeda militants.
"I will reiterate is that we've been working closely with the new civilian government of Pakistan that is feeling its way and working to establish itself," said Perino.
She said the two allies faced "a common enemy" in the Taliban Islamist militia and the Al-Qaeda terrorist network and noted "a very big scare yesterday" with a failed attack on Pakistan Prime Minister Yousuf Raza Gilani.
"We have a lot of cooperation that's ongoing with them and a lot of need to increase communication," said Perino.
Asked for the underlying rationale for not commenting on the reported strike, Perino replied: "All I can tell you is that I am going to decline to comment on reports about that incident."
Pakistani Prime Minister Yousuf Raza Gilani warned US President George W Bush in July against acting "unilaterally" against Islamic militants in Pakistan.