Acting Drug Enforcement Administration (DEA) chief Chuck Rosenberg repudiated President Trump's comments last week about how arrested individuals should be treated.

"The President, in remarks delivered yesterday in New York, condoned police misconduct regarding the treatment of individuals placed under arrest by law enforcement," Rosenberg wrote Saturday in a staff memo obtained by CBS News' Paula Reid.

The Wall Street Journal first reported Rosenberg's memo to DEA staffers.

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Mr. Trump had doled out some arrest advice for police officers at a speech on Friday in Long Island.

"When you see these thugs being thrown into the back of a paddy wagon, you just see them thrown in -- rough -- I said, 'Please don't be too nice.' Like when you guys put someone in the car and you're protecting their head [with your hand], ... like don't hit their head, and they've just killed somebody ... I said, 'you can take the hand away.'"

It was a comment White House press secretary Sarah Huckabee Sanders dismissed. "I believe he was making a joke at the time," she told a reporter who asked about the comments.

But Rosenberg, who is a close friend of fired FBI Director James Comey, did not take the president's comments lightly.

While he said in his memo that he didn't believe DEA agents would mistreat defendants, he nonetheless wished to reaffirm "the operating principles to which we, as law enforcement professionals, adhere."

And, he said he was writing "because we have an obligation to speak out when something is wrong. That's what law enforcement officers do. That's what you do. We fix stuff. At least, we try," he wrote.

He went on to urge staff to live up to the agency's core values, including rule of law, respect, integrity, and accountability, among other traits. "This is how we conduct ourselves," he directed. "This is how we treat those whom we encounter in our work: victims, witnesses, subjects, and defendants. This is who we are."