Speaking in Laos, Mr. Obama said that every time Mr Trump spoke it became clearer that the Republican contender was not qualified to be president, Censor.NET reports citing BBC.
In a televised forum on Wednesday, Mr Trump had praised Mr Putin's "great control" and 82% approval rating. Mr Obama said: "I don't think the guy's qualified to be president of the United States and every time he speaks, that opinion is confirmed."
"You actually have to know what you are talking about and you actually have to have done your homework. When you speak, it should actually reflect thought-out-policy you can implement."
Mr. Trump had told the forum in New York that the Russian president had "been a leader far more than our president has been".
Quizzed by NBC host Matt Lauer on his previous complimentary remarks about Mr Putin, Mr Trump responded: "He does have an 82% approval rating."
"I think when he calls me 'brilliant', I'll take the compliment, OK?" said the businessman, adding that Putin had "great control over his country."