Ian Bremmer, president of the political risk consultancy Eurasia Group, told CNBC on Wednesday he reported on a second, undisclosed G-20 meeting between President Donald Trump and Russian President Vladimir Putin because "nobody else was going to break it."

Saying he's not in the business of breaking news, Bremmer told "Squawk on the Street" he decided to talk about it Monday evening with Bloomberg's Charlie Rose to have a longer conversation as opposed to just making headlines. After that, the story went national.

Trump-Putin had a 2nd private discussion at the G20...for an hour. Really? Really. I discuss with @charlierose.

In a note to Eurasia clients Monday morning, Bremmer first disclosed the G-20 dinner meeting between Trump and Putin, which took place on July 7, just hours after the two leaders held their formal, two-hour bilateral meeting at the summit in Germany.

The White House on Tuesday confirmed the second meeting, describing the encounter as "a brief conversation at the end of a dinner."

Bremmer took issue with that characterization, and indicated others knew about the meeting.

The dinner meeting "might have been 55 minutes," he told CNBC. "The people I talked to weren't timing. It wasn't five minutes. Brief implies it's five minutes or 10 minutes."

In details from the Eurasia note, Bremmer wrote about the sequence of events, according to his sources.

Halfway in [the dinner], Trump gets up from his seat, sits next to Putin, and spends roughly an hour talking privately and animatedly with the Russian president, joined only by Putin's own translator. ... Several notable pieces here. One, that Trump didn't bring in his own translator — a breach of national security protocol Trump likely wouldn't be aware of, but that significantly advantages the meeting towards Putin.

In a late Tuesday tweet, Trump angrily responded the story.

"Fake News story of secret dinner with Putin is "sick." All G 20 leaders, and spouses, were invited by the Chancellor of Germany. Press knew!"

The Fake News is becoming more and more dishonest! Even a dinner arranged for top 20 leaders in Germany is made to look sinister!

Bremmer told CNBC he didn't think the meeting was "sinister" either, but said it showed a lack of experience and indifference on the part of Trump.

"He's going to get played. He's going to get played. That's the concern," he said.

On Wednesday morning, Bremmer tweeted his conclusions.

Tweet: Bremmer

The White House did not immediately respond to a request for comment.