“Transparency is important, but we expect the White House to insist that no reform will compromise the operational integrity of the program,” said the spokesman, Brendan Buck. “That must be the president’s red line, and he must enforce it. Our priority should continue to be saving American lives, not saving face.”

A clear theme of Mr. Obama’s remarks was that he believed that the public’s understanding of the surveillance programs had been distorted. He portrayed some of Mr. Snowden’s leaks as having been reported in “the most sensationalized manner possible” and parceled out to “maximize attention” in “dribs and in drabs, sometimes coming out sideways.” The result has been misimpressions not merely among the American public, he said, but around the world — a reference to the widespread international criticism of the United States over reports of its surveillance policies.

“If you are the ordinary person and you start seeing a bunch of headlines saying ‘U.S. Big Brother looking down on you, collecting telephone records, etc.,’ well, understandably people would be concerned,” he said, while also addressing some of his reassurances to those abroad.

“To others around the world, I want to make clear once again that America is not interested in spying on ordinary people,” he said. “Our intelligence is focused above all on finding the information that’s necessary to protect our people and, in many cases, protect our allies. It’s true we have significant capabilities. What’s also true is we show a restraint that many governments around the world don’t even think to do.”

In an effort to rebuild public trust, Mr. Obama said he wanted to work with Congress to modify the phone log program, but in what he said would be an “appropriate” way. He listed as examples of those steps establishing more oversight and auditing how the database is used.

The president also threw his support behind a proposal to change the procedures of the secret court that approves electronic spying under the Foreign Intelligence Surveillance Act, saying an adversarial lawyer should make arguments opposing the Justice Department when the court is considering whether to approve broad surveillance programs.