"I was honestly concerned that he might lie about the nature of our meeting and so I thought it really important to document," Comey told the Senate Intelligence Committee.
"No, I can definitively say the president’s not a liar," White House spokeswoman Sarah Sanders said.
"And it’s frankly insulting to be asked that."
Trump is committed to ensuring that US election is conducted fairly and protected from any interference, she added.
"The president takes our elections very seriously."
She added that the US president won't lift anti-Russian sanctions over Ukraine until the Minsk deal is implemented.
In the written statement to the panel released on Wednesday, Comey accused Trump of pressing him to drop the FBI probe into former National Security Adviser Michael Flynn's relations with Russia.
On May 9, the White House announced President Donald Trump's decision to remove James Comey from the Federal Bureau of Investigation (FBI) director post on recommendations of the US attorney general and his deputy.
