Several current and former officials played down the significance of placing the classified calls into the secure system, saying it made sense to restrict the calls given the number of leaks from the Trump White House.

Nevertheless, the use of the system has come under scrutiny after the unclassified version of the whistle-blower complaint was made public. The complaint raised questions that the July 25 call with the Ukrainian president had been improperly placed in the classified system, suggesting that officials put the reconstructed transcript into a system meant to protect the nation’s most sensitive secrets.

The Trump administration said on Friday that National Security Council lawyers had made the decision to place the reconstructed transcript of that phone call into a highly classified computer system accessible to only a small number of officials.

“N.S.C. lawyers directed that the classified document be handled appropriately,” said a senior administration official. The statement was also first reported by CNN.

But the official did not actually say how the document was handled, nor address the whistle-blower’s specific charge that the reconstructed transcript, in what would be a highly unusual action, was moved from a computer system widely accessible to National Security Council officials to one reserved for those with code-word clearance to handle the country’s most closely guarded secrets like covert operations and foreign surveillance.

A White House spokesman did not respond when asked about that specific claim. Democrats in Congress and former N.S.C. officials and lawyers in both parties have said such an action, if motivated by a desire to conceal Mr. Trump’s efforts to put political pressure on the Ukrainian leader, would be far from appropriate, and at a minimum, unethical. But in a combative exchange with reporters later in the day, Kellyanne Conway, a White House counselor, repeated the spokesman’s language, saying that “as I understand, the document was handled appropriately at all times.”

“I think the most important thing about said document is that the whole world has access to it now,” Ms. Conway said, citing its release by the White House this week.