“I am having trouble putting food on the table and paying the rent,” he said.

He said he posted the Instagram image without thinking that a photograph of Judge Jackson that appeared to include the cross hairs of a gun sight might threaten the safety of the judge or others. “I can’t rationalize my thinking because I wasn’t thinking,” he said.

The judge firmly rejected that explanation. As a veteran political propagandist, she said, “Roger Stone fully understands the power of words and the power of symbols.” She added, “There is nothing ambiguous about cross hairs.”

Judge Jackson said Mr. Stone was so obviously eager for public attention that only a strict gag order would curb him from using his public platform to incite his followers with incendiary comments. Although he insisted he was deeply sorry for his actions, she said his apologies rang “hollow.” And she said his “evolving” story about the origin of the Instagram post was not credible.

“Mr. Stone could not even keep his story straight on the stand, much less from one day to another,” she said. The lead prosecutor in the case, Jonathan Ian Kravis, an assistant United States attorney, also accused Mr. Stone of dissembling when he insisted that he could not remember who might have given him photos of Judge Jackson to choose from.

“You cannot remember the names of all the volunteers who worked for you four days ago?” he asked.

Mr. Stone’s post came days after Judge Jackson had restricted Mr. Stone from making public statements on the courthouse steps that “pose a substantial likelihood of material prejudice to this case.” Her new order imposes the same restrictions on him that she has placed on lawyers in the case.

“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,” Judge Jackson said. She said her order also applied to surrogates who might speak on Mr. Stone’s behalf.

She said Mr. Stone could continue to seek donations to his legal defense fund, but could note only that he had pleaded not guilty — without commenting on the judge, the prosecutors, the witnesses or anyone involved in the case.