A federal judge has completely barred former Trump political adviser Roger Stone from speaking publicly about his ongoing prosecution on obstruction and false statement charges, after a picture of the judge appeared on Stone's Instagram this week with what appeared to be crosshairs in the background.

The ruling followed a hearing on Thursday in which Stone took the stand to insist he was "heartfully sorry" for the picture, which Stone said he had reviewed prior to posting it -- although he suggested someone else had first selected the image.

U.S. District Court Judge Amy Berman Jackson tore into Stone during the proceeding, saying she simply didn't believe his explanation that an unnamed "volunteer" was to blame.

"I have serious doubts about whether you learned anything at all," Jackson said. "From this moment on, the defendant may not speak publicly about this case -- period. No statements about the case on TV, radio, print reporters, or Internet. No posts on social media. [You] may not comment on the case through surrogates. You may send out emails about donating to the Roger Stone defense fund."

Jackson added an apparent threat to revoke Stone's bail and send him to jail: "This is not baseball. There will be no third chance. If you cannot abide by this, I will be forced to change your surroundings so you have no temptations."

Jackson had issued a limited gag order in Stone's case last week, preventing him from discussing the case near the courthouse. Stone was being questioned Thursday by Jackson and government lawyers as to why Jackson should not take action in response to the image.

On Thursday, Stone made the risky decision to take the stand, after an initial series of questions from Jackson to Stone's lawyer, Bruce Rogow.

The longtime Trump confidante walked into court wearing his signature circle framed glasses, but took them off before Jackson entered the courtroom. Stone's wife and daughter sat in the front row.

Under questioning from prosecutors and Jackson, the 66-year-old Stone -- who frequently looked directly at Jackson as he spoke -- said the image had been selected by a volunteer who was working for him, though he couldn't say who picked the photo or list the five or six volunteers who have been working for him when he was asked by prosecutors.

He said he had several photos to choose from and posted the image himself to his profile.

"You had a choice?" the judge interjected.

Stone said he picked the photo "randomly," a suggestion the judge almost immediately dismissed.

"It was an egregious mistake. I obviously wish I could do it over again, but I cannot," Stone said. "I recognize I let the court down, I let you down, I let myself down. ... It was a momentary lapse in judgment."

He has said the photo was "misinterpreted," the symbol was actually the Celtic cross, not crosshairs of a gun, and he was not trying to threaten the judge. But, he added, he wasn't sure what the symbol meant, because "I’m not into the occult."

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At one point during Thursday's hearing, Rogow called the post that featured Jackson's image "indefensible." Jackson replied: "I agree with you there."

"I am under enormous pressure," Stone testified. "I now have TV people saying I will be raped if I go to jail. I'm having trouble putting food on the table and paying the rent." (Indeed, CNN senior political analyst David Gergen pondered on air Monday if Stone -- whom he called a "dandy" -- would be raped in prison.)

Stone deleted the Instagram photo shortly after posting it, but later posted the same one again, this time without the apparent crosshairs.

In court, Stone said he "didn’t recognize it as a crosshair" and "didn't notice" a crosshair in the image.

"This was a screwup," Stone said. "I admit it."

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Jackson reminded Stone before his testimony that he would be subject to government cross-examination and was under oath. Asked whether he understood the picture could be construed as a threat, Stone replied: "I now recognize that. … I can’t rationalize my thinking because I wasn’t thinking, and that’s my fault."

"I am kicking myself for my own stupidity, but not more than my wife is kicking me," Stone later told Jackson. He added that "my consulting business has dried up" and said, "I've exhausted my savings."

"This is not baseball. There will be no third chance." — U.S. District Court Judge Amy Berman Jackson

Stone has pleaded not guilty to charges he lied to Congress, engaged in witness tampering and obstructed a congressional investigation into possible coordination between Russia and President Trump's 2016 presidential campaign. The charges stem from conversations he had during the campaign about WikiLeaks, the anti-secrecy group that released material stolen from Democratic groups, including Hillary Clinton's campaign.

The political operative and self-described dirty trickster is the sixth Trump aide or adviser charged in Mueller's investigation. He was arrested last month and has remained free on a $250,000 personal recognizance bond. Stone has maintained his innocence and blasted the special counsel's investigation as politically motivated.

Fox News' Jake Gibson, Kelly Phares, Adam Shaw, and The Associated Press contributed to this report.