"'He's (Trump's) lost it.'" Trump attacked Wolff - in a tweet - a day before the latter's book was released as well.
"It's a disgrace that he can do something like this", Trump said of the book, which was released on Friday and contained damaging allegations about his presidency.
In his tweet, Trump also targeted his one-time pal Steve Bannon - he called him "sloppy" - whom he unceremoniously dumped from his position as White House strategist in August, nearly exactly a year after hiring him. "Too bad!", tweeted Trump.
"I absolutely spoke to the president. I think more and more people are starting to see that his facts just simply don't add up".
In his interview with the BBC, Wolff was asked if he believed that Bannon felt Trump was unfit to serve as president and would try to bring him down. Full of lies, misrepresentations and sources that don't exist.
Trump's mute button isn't working.
While several analysts, as well as Trump allies, questioned the veracity of some of Mr Wolff's claims, the controversy has increased pressure on Trump, particularly in relation to comments attributed to Mr Bannon about the investigation into ties between his presidential campaign and Russian Federation.