"Hoping and telling are two very different things," the younger Trump tweeted. "Knowing my father for 39 years, when he 'orders or tells' you to do something there is no ambiguity, you will know exactly what he means."
Administration spokeswoman Sarah Sanders tried to project an air of normalcy, telling reporters, "It's a regular Thursday at the White House."
She said the president spent much of the morning in meetings with his national security team, although a person close to his legal team said Trump planned to watch at least part of the Comey hearing with his attorney.
Sanders declined to answer specific questions about Comey's testimony, referring those to the president's lawyer. She did take issue, though, with Comey's claim that Trump is less than honest.
"I can definitely say the president is not a liar," Sanders said. "And I think it's frankly insulting that that question would be asked."
Comey accused Trump of lying in multiple instances in the hearing.
Trump later addressed the Faith and Freedom Coalition, a group of religious conservatives who have been supportive of the president. He made no direct reference to the Comey hearing in his speech, though he did liken himself to people of faith who feel persecuted by the government.
"As you know, we're under siege," Trump said, promising to protect religious liberty. "You understand that. But we will come out bigger and better and stronger than ever."
Republican House Speaker Paul Ryan defended the president's contacts with Comey, saying any breach of the usual firewalls was a product of inexperience, not nefarious intent.
"Of course there needs to be a degree of independence" between the FBI and the White House, Ryan said. "The president is new at this. He's new to government. So he probably wasn't steeped in the long-running protocols that establish the relationships."
During the hearing, Comey offered a different take.
"Why did he kick everybody out of the Oval Office" before raising the Flynn investigation, if the president's intent was innocent? Comey asked.
"That, to me, as an investigator, is a very significant fact."