STORY: In a written order, Justice Juan Merchan said the fine may not be enough to serve as a deterrent for the wealthy businessman-turned-politician and lamented he did not have the authority to impose a higher penalty.

"Defendant is hereby warned that the Court will not tolerate willful violations of its lawful orders and that if necessary and appropriate under the circumstances, it will impose an incarceratory punishment," Merchan wrote.

Merchan had imposed the gag order to prevent Trump from criticizing witnesses and others involved in the case.

The judge fined Trump $1,000 for each of nine online statements that he said violated his order not to criticize witnesses or other participants in the trial. Prosecutors had flagged 10 posts as possible violations.

"This gag order is not only unique, it's totally unconstitutional," said Trump.