In an unusual break with typical Supreme Court practice, Chief Justice John Roberts on Wednesday delivered a mild rebuke of President Donald Trump for calling a federal judge in California an "Obama judge."

Roberts said that America does not have "Obama judges or Trump judges, Bush judges or Clinton judges."

"What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them," Roberts said in a statement responding to an inquiry from the Associated Press. "That independent judiciary is something we should all be thankful for."

Trump on Tuesday lashed out against Jon Tigar, a district court judge in California, who issued a forceful ruling Monday night blocking the president's attempt to bar entry to the U.S. to migrants who arrive between ports of entry.

"This was an Obama judge," Trump told reporters. "And I'll tell you what, it's not going to happen like this anymore."

Trump also repeated his attacks on the San Francisco-based 9th Circuit Court of Appeals, which has dealt his administration a number of legal setbacks.

"The 9th Circuit is really something we have to take a look at because it's – because it's not fair," Trump said. A spokesperson for the 9th Circuit did not respond to a request for comment about the president's remarks.

In a post on Twitter Wednesday, the president reasserted his attacks.

"Sorry Chief Justice John Roberts, but you do indeed have 'Obama judges,' and they have a much different point of view than the people who are charged with the safety of our country," the president wrote.

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Trump was criticized last year for calling a federal judge who ruled against a version of his administration's travel ban a "so-called judge."

The nine justices on the court typically avoid making statements to the public that can be perceived as partisan.

That effort has been on display in recent weeks as the court's liberals have sought to demonstrate public harmony in the wake of the contentious confirmation hearings for the most recent addition to the court, Justice Brett Kavanaugh. On Saturday, Justice Sonia Sotomayor, an Obama nominee to the court, told CNN that Kavanaugh is now part of the Supreme Court "family."

There are occasionally divergences from the norm. Justice Ruth Bader Ginsburg disparaged Trump during his campaign for president, calling him a "faker" and jokingly suggesting it was time to move to New Zealand. But before the election was over, Ginsburg apologized for her remarks and said she regretted making them.

Carl Tobias, a law professor at the University of Richmond who is an expert on the federal courts, said that Roberts has been extremely guarded in his public remarks, limiting any discussion of the other branches to the occasional gentle chiding of Congress in his year-end report.

Wednesday's statement, Tobias said, shows that Roberts is "very concerned about the judicial independence of the judges who the president continues to attack, sometimes very personally."

"If Roberts believes in anything, it's his own coequal branch being independent of the other branches," Tobias said.