Trump told Putin he was going to 'act a little tougher' in front of the cameras: New book
US president Donald Trump and Russian president Vladimir Putin met for face-to-face talks in Osaka in 2019. (AFP)

Former president Donald Trump once told Russian President Vladimir Putin he was going to "act a little tougher" in front of the news cameras, according to a new book from former White House press secretary Stephanie Grisham.

The incident occurred during a 2019 meeting in Osaka, Japan, according to the Washington Post, which obtained a copy of Grisham's forthcoming book, "I'll Take Your Questions Now."

The Post reports that "little is known" about a 90-minute private conversation that occurred between Trump and Putin.

"But as journalists were quickly ushered out of the room at the 2019 Group of 20 Summit, Stephanie Grisham once again found herself with a close-up view of the action," the newspaper reports.

"She saw Trump lean toward Putin that day and tell him: 'Okay, I'm going to act a little tougher with you for a few minutes. But it's for the cameras, and after they leave, we'll talk. You understand.'"

Trump then "quickly" and "playfully" told Putin not to meddle in U.S. elections, USA Today reported at the time.

"Don't meddle in the election, president," Trump said in a joking manner, wagging his finger at Putin.

"When an interpreter translated Trump's 'request,' Putin laughed," USA Today reported.