The White House sought on Friday to distance itself from the National Security Agency's monitoring of foreign leaders, rejecting criticism that President Barack Obama was understating his knowledge of the agency's activities.

In a further sign of the growing blame game within Washington over the affair, spokesman Jay Carney said Obama paid close attention to terrorism intercepts but had no need to personally bug the phones of allies.

"The president is a very deliberate consumer of the intelligence gathered for him on national security matters," said Carney. "But when the president wants to find out what the heads of state of friendly nations think, he calls them."

The White House comments followed an admission on Thursday from secretary of state John Kerry that some surveillance practices were carried out "on auto-pilot" and had not been known to the president. That was followed on Thursday night by the NSA director, Keith Alexander, blaming Kerry's own department for driving its spying on friendly world leaders.

"The intelligence agencies don't come up with the requirements. The policymakers come up with the requirements," Alexander said. "One of those groups would have been, let me think, hold on, oh: ambassadors."

Alexander said the NSA collected information when it was asked by policy officials to discover the "leadership intentions" of foreign countries. "If you want to know leadership intentions, these are the issues," he said.

On Friday, veteran US diplomats questioned that assertion.

Thomas Pickering, who served as ambassador to Russia, India, Israel, Jordan and the United Nations, said he found it puzzling that intelligence agencies would interpret requests for information as a green light to bug the phones of friendly government leaders.

"To point the finger at ambassadors as being responsible for generating these requests seems, in my experience, to be far fetched," Pickering told the Guardian.

"In my time, intelligence requirements were never based on collection methods, they were based on intelligence interests. That an ambassador may have been interested in the views of a foreign leader is not a reason to say they had any responsibility for how that information was gathered."

Pickering, who recently led a White House review of the 2012 assassination of the US ambassador to Libya, said he had no direct knowledge but would be surprised to find the NSA was taking direction from ambassadors on such matters.

"It would be self-evident that embassies would be interested in knowing, but it is a huge jump to imagine that an ambassador could somehow be so persuasive as to persuade the intelligence community," he said.

NSA director General Keith Alexander. Photograph: Evan Vucci/AP

Alexander's explanation also drew scorn from James Carew Rosapepe, who served as an ambassador under the Clinton administration, who said "we generally don't do that in democratic societies" during an event at the the Baltimore Council on Foreign Relations on Thursday.

Pressed over the apparent "inconsistency" between comments by Alexander and Kerry, Jen Psaki, the state department's chief spokeswoman, said on Friday: "I don't actually think there was an inconsistency … I would just refute the notion of the question."

She added that the reviews into surveillance programs announced by the White House included all branches of government, and that Kerry's remarks applied not just to the state department.

"When the secretary made his comments yesterday, he said 'we'," she said. "He is talking about a collective 'we', as in the entire government is looking at these programs."