The Kremlin is already seizing on Trump's comments casting doubt that Russia meddled in the 2016 election
Petrov told Bloomberg News that Trump had highlighted "equally the possibility that it could have been other countries.
"Please note the nuances," he said.
Trump's comments, made at a joint news conference in Warsaw alongside Polish President Andrzej Duda, had appeared to undercut the conclusion reached by several intelligence agencies that determined Russia was to blame. Russia has consistently denied meddling in last year's election.
"I think it was Russia, but I think it was probably other people and/or countries," Trump told reporters. "Nobody really knows. Nobody really knows for sure.
"Everybody was 100% sure that Iraq had weapons of mass destruction. Guess what? That led to one big mess. They were wrong, and it led to a mess," he added.
Trump instead cast blame on President Barack Obama for not acting aggressively enough to counter foreign interference.
"They say he choked. Well, I don't think he choked," Trump said. "I think he thought Hillary Clinton was going to win the election, and he said, 'Let's not do anything about it.'"
Trump is set to meet Russian President Vladimir Putin for the first time as president Friday, but the White House has said there's "no specific agenda" for their discussion.