The judge in Donald Trump's hush money trial said the former president was "cursing audibly" during testimony on Tuesday by porn star Stormy Daniels and directed his lawyers to temper their client's behavior.

"I understand that your client is upset at this point, but he is cursing audibly, and he is shaking his head visually, and that's contemptuous," Judge Juan Merchan told Trump attorney Todd Blanche during a sidebar conversation, according to excerpts of the official trial transcript posted online Tuesday evening.

Daniels was testifying in an extraordinary courtroom face-off with Trump about the night she allegedly slept with the Republican in a hotel penthouse in 2006.

She gave at times explicit details of the alleged affair, which Trump has denied. He is accused of falsifying business records to cover up a $130,000 hush money payment to Daniels over the affair ahead of the 2016 election that brought him to power. 

Merchan said Trump's noise and gestures "has the potential to intimidate the witness and the jury can see that," later adding: "I won't tolerate that."

He said he was raising this during the sidebar, when lawyers huddle with the judge in conversations that are not meant to be audible to the jury or wider courtroom, because "I don't want to embarrass him."

He said he noticed Trump shaking his head in particular when Daniels discussed swatting the billionaire with a magazine.

"I will talk to him," Blanche promised.

Trump's attorneys tried unsuccessfully Tuesday to have a mistrial declared based on Daniels's testimony.

Speaking to reporters after the day's proceedings, Trump -- who is running for president again this year -- called the case a "disgrace" and said he "should be out campaigning right now."