President Donald Trump has repeatedly dismissed intelligence reports of Russian meddling in the election as fake news, a hoax and made-up.
Bush, interviewed on stage at a business conference in the capital of the United Arab Emirates, said there was clear evidence that the Russians had meddled but whether that affected the outcome of the election was another question. "Our democracy is only as good as people trust the results", Bush added.
Bush also took a swipe at Russian President Vladimir Putin, whom he referred to as "zero sum", and said he "has a chip on his shoulder".
"He said he didn't meddle", Trump told reporters on Air Force One. "He said he absolutely did not meddle in our election".
The Kremlin has repeatedly denied accusations by United States intelligence officials and others of interfering in foreign elections, including the 2016 U.S. vote. "He can't think, 'How can we both win?' He only thinks, 'How do I win, you lose?'"
"He's resentful", Bush said of Putin.
In October, Bush said the Russian government "made a project of turning Americans against each other".
In the talk, Bush also criticized the Trump administration's decision to scrap protection for "dreamers", young illegal immigrants brought to the U.S.as children granted protection from deportation, citing that "America's their home".
"But foreign aggressions - including cyber-attacks, disinformation and financial influence - should not be downplayed or tolerated", Bush said at the time. Democrats immediately rejected the proposal.
On Thursday, he took part in a summit in Abu Dhabi organized by the Milken Institute, a group of economic studies based in California. He was sentenced to a decade in prison but served less than two years after a judge reduced his sentence.