The Hollywood star, 70, lambasted Mr Trump for his approach, accusing him of acting like a fan instead of a world leader during their Helsinki press conference which saw him side with Mr Putin over his own security services.
“It was embarrassing,” Schwarzenegger said in a video. “You stood there like a little wet noodle. Like a fan boy. I was asking myself ‘when are you going to ask him for a selfie and an autograph?’
He accused Mr Trump of ‘selling out’ his intelligence community, the justice system, and “worst of all, our country”.
— Arnold (@Schwarzenegger) July 16, 2018
He continued: “You’re the President of the United States, you shouldn’t do that. What’s the matter with you?”
Schwarzenegger accused Mr Trump of lacking the courage of past US Presidents in the face of Russia, asking: “What happened to the strong words and the strength of Ronald Reagan when he stood there at the Berlin Wall and said ‘Mr. Gorbachev, tear down this wall’?
“What happened to all that?”
He shared the clip with his 4.2 million Twitter followers, captioning the post: “President @realDonaldTrump, remember, America first.”
Fans praised the Terminator actor, with many calling for him to run against Mr Trump in the 2020 presidential elections.
One user tweeted: “Dear Candidate US President, Mr.@Schwarzenegger; We hope Mr President @realDonaldTrump can hear you. And for the next US President, The People Waiting you (sic).”
Another posted simply: “@Schwarzenegger for President!”
Mr Trump was branded “treasonous” after he refused to criticise Mr Putin over meddling in the 2016 US presidential election, despite the US intelligence community concluding it was orchestrated by the Kremlin.
Mr Trump said the Russian collusion investigation has been a “disaster” for the US and has “separated” America and Russia.