Sean Spicer, the White House press secretary, did not dispute the account.
In a statement, he said that Mr. Comey had put unnecessary pressure on the president’s ability to conduct diplomacy with Russia on matters such as Syria, Ukraine and the Islamic State.
“By grandstanding and politicizing the investigation into Russia’s actions, James Comey created unnecessary pressure on our ability to engage and negotiate with Russia,” Mr. Spicer said. “The investigation would have always continued, and obviously, the termination of Comey would not have ended it. Once again, the real story is that our national security has been undermined by the leaking of private and highly classified conversations.”
The day after firing Mr. Comey, Mr. Trump hosted Russia’s foreign minister, Sergey V. Lavrov, in the Oval Office, along with the Russian ambassador to the United States, Sergey I. Kislyak. The meeting ignited controversy this week when it was revealed that Mr. Trump had disclosed intelligence from an Israeli counterterrorism operation.
A third government official briefed on the meeting defended the president, saying Mr. Trump was using a negotiating tactic when he told Mr. Lavrov about the “pressure” he was under. The idea, the official suggested, was to create a sense of obligation with Russian officials and to coax concessions out of Mr. Lavrov — on Syria, Ukraine and other issues — by saying that Russian meddling in last year’s election had created enormous political problems for Mr. Trump.
The president has been adamant that the meddling did not alter the outcome of the race, but it has become a political cudgel for his opponents.
Many Democrats and some Republicans have raised alarms that the president may have tried to obstruct justice by firing Mr. Comey. The Justice Department’s newly appointed special counsel, Robert S. Mueller III, was given the authority to investigate not only potential collusion, but also related allegations, which would include obstruction of justice.
The F.B.I.’s investigation has bedeviled the Trump administration, and the president personally. Mr. Comey publicly confirmed the existence of the investigation in March, telling Congress that his agents were investigating Russian efforts to influence the outcome of the presidential election and whether anyone in the Trump campaign had been involved. Mr. Trump has denied any collusion and called the case a waste of money and time.
At first, the White House said Mr. Trump fired Mr. Comey based on the recommendation of the Justice Department, and because of Mr. Comey’s handling of the F.B.I. investigation into Hillary Clinton last year. Officials said it had nothing to do with the Russia investigation.
But the president undercut that argument a day later, telling NBC News, “When I decided to just do it, I said to myself — I said, you know, this Russia thing with Trump and Russia is a made-up story.”