TEHRAN, Young Journalists Club (YJC) - "The use of the terms 'secret' or 'confidential' for this meeting provokes absolute surprise and incomprehension," said Kremlin spokesman Dmitry Peskov on Wednesday.
He added that the meeting had been "officially accepted" by diplomatic channels.
"There was no secret and confidential meeting… To say so is absolutely absurd," he added.
On Tuesday, White House Press Secretary Sean Spicer confirmed that the two had an informal talk during the dinner at the G20 summit in the German city of Hamburg on July 7, several hours after their first formal bilateral sit-down.
US National Security Council spokesman Michael Anton also acknowledged that a second meeting had taken place at the world leaders’ dinner, with Trump leaving his seat to occupy an empty chair next to Putin.
News of the second encounter came as Trump was struggling at home with a deepening scandal over alleged Russian efforts to help him defeat his rival Hillary Clinton in last year’s White House race.
The scandal has now entangled his eldest son, Donald Trump Jr, who last week released emails purportedly showing he embraced Russia's efforts to support his father's presidential campaign, and admitting he would "love" to get dirt from Moscow on Clinton, Presstv reported.
Trump later defended his son, praising his "transparency" for releasing the email chain and again condemning the investigation about whether Moscow helped him win the White House last November.