President Obama has told Francois Hollande that the US is no longer spying on France.
The two leaders spoke by phone after Wikileaks documents claimed the US had spied on Hollande and his two predecessors.
Mr Obama said the US "are not targeting and will not target" the communications of the French president.
Francois Hollande, the French president, has branded as "unacceptable" the reported spying by the US on three French presidents.
The allegations that the National Security Agency spied on Hollande, and before him presidents Jacques Chirac and Nicolas Sarkozy, were made by Wikileaks, which cited intelligence reports.
"France will not tolerate actions that threaten its security and the protection of its interests," Hollande's office said in a statement.
"Commitments were made by the US authorities. They need to be recalled and strictly respected."
The US ambassador to Paris was summoned to the French foreign ministry on Wednesday over the claims.
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.