US President Donald Trump said he had "good discussions" with Russian leader Vladimir Putin when they met briefly at an Asia-Pacific summit in Vietnam.
On Twitter, he blasted "haters and fools", who, he said, do not encourage good relations between the countries.
Earlier he said Mr Putin told him he was insulted by allegations of Russian interference in the 2016 US election.
The US intelligence community has previously concluded that Russia tried to sway the poll in Mr Trump's favour.
"He said he absolutely did not meddle in our election," the US president said.
However, after intense criticism, Mr Trump clarified hat he supported US intelligence agencies in their conclusion. "As to whether or not I believe it or not, I'm with our agencies. I believe in our... intelligence agencies," he said.
"What he believes, he believes," he added, of Mr Putin's belief that Russia did not meddle.
The two leaders had no formal bilateral talks during the Asia-Pacific Economic Co-operation (APEC) event, but meet in passing on three occasions. They spoke about the Syria crisis and the election allegations, according to Mr Trump.
Republican Senator John McCain, a vehement critic of Mr Trump, called him naive for "taking the word of a KGB colonel over that of the American intelligence community".
A CIA statement passed to US media said: "The intelligence assessment with regard to Russian election meddling has not changed."
In his tweets, Mr Trump also said his predecessor, Barack Obama lacked "chemistry" with President Putin.
The US justice department has appointed special investigator Robert Mueller to examine any possible collusion involving Mr Trump's team, and legal action has already been taken against several former aides.
How did the two presidents get on in Vietnam?
Mr Trump and Mr Putin met for the first time in July at a G20 summit in the German city of Hamburg. In Da Nang they were seen
They had warm words for each other, with the US president talking of their mutual "very good feeling" and the Russian leader describing his counterpart as "well-mannered... and comfortable to deal with".
They did manage to sign off a statement vowing to continue the battle against so-called Islamic State in Syria until the militants are defeated and calling for a political solution to the conflict.
How far has US justice department investigation progressed?
Last month, former Trump campaign adviser George Papadopoulos pleaded guilty to having lied to the Federal Bureau of Investigation (FBI) about the timing of meetings with alleged go-betweens for Russia.
He testified that Russian nationals had contacted him in an attempt to gain influence with the Trump campaign, offering "dirt" in the form of "thousands of emails" on Mrs Clinton in April 2016 - two months before the DNC emails were leaked.
Mr Trump has played down the importance of Mr Papadopoulos, calling him a "low-level volunteer" and "liar".
On Saturday, Mr Putin brushed aside US media reports that a woman wrongly identified by Mr Papadopoulos as the Russian president's niece had offered to help broker meetings with Kremlin officials.
"I do not know anything about it and I think it is just some fantasies," Mr Putin said.
Mr Trump's former campaign manager, Paul Manafort, and an associate were also placed under house arrest on charges of money laundering as a result of the Mueller inquiry, but the charges do not relate to the election.
briefly on three occasions within 24 hours during the Asia-Pacific Economic Co-operation (APEC) summit.
However, they had no formal bilateral meeting, with Mr Putin blaming it on scheduling and protocol.