Biden talked about how he was inspired by the white supremacist caucus and former President Donald Trump's reaction to running for the White House in the 2020 term, and then recounted the same conversation just two minutes later.
"Sometimes I talk back and tell the story, I think it's important to note that the president was speaking, as I said at a fundraiser, and he was speaking from his heart," Pierre said with a laugh.
This comes at a time of doubts ahead of the upcoming presidential elections about the eligibility of the octogenarian president to run again.
Last week, Biden, the oldest U.S. president in U.S. history, said he understood the focus on his age but would run for the White House because Donald Trump wanted to "destroy" American democracy.
The 80-year-old president usually avoids the issue of age but touched on it during a fundraiser at a Broadway theater in New York, explaining that his experience has helped him deal with crises such as the war in Ukraine and the Covid pandemic.
Biden added: "A lot seem to be focusing on my age. I understand that, believe me, I know that better than anyone else."
"I will run because democracy is at stake, because in 2024 the fate of democracy will be tied to the ballot again, let it be clear, Donald Trump and his Republican supporters are determined to destroy American democracy."
Polls show U.S. voters have concerns about Biden's age ahead of next year's potential contest against Trump.
Biden, who will attend the U.N. General Assembly in New York this week, will turn 86 at the end of his second term if he wins the next presidential election.