Bitcoin has gained a lot of fans recently, but Goldman Sachs CEO Lloyd Blankfein is not one of them.

In an interview with CNBC's Kayla Tausche, he said that "maybe bitcoin is a kind of a bubble," adding: "I don't like it. I'm not comfortable with it."

Blankfein's reason for not trusting the cryptocurrency is simple, he said: "I'm kind of an old dog to be absorbing that kind of a new trick."

Bitcoin has soared more than 600 percent this year. On Thursday, the cryptocurrency traded down 3.9 percent at $7,172.80, but remained near a record high.