President Donald Trump is taking another swipe at the Federal Reserve, expressing concern in an interview with Reuters that the central bank is raising interest rates after years of holding borrowing costs near zero.

"I'm not thrilled with his raising of interest rates, no. I'm not thrilled," Trump said in the interview, referring to Fed Chairman Jerome Powell.

"I should be given some help by the Fed," Mr. Trump added, according to a Reuters tweet.

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The president has repeatedly complained about the Fed's raising interest rates in recent weeks. Mr. Trump also complained about such monetary tightening at a fundraiser on Friday, as well as during a dinner earlier this month at his New Jersey golf club, according to the Wall Street Journal. In July, Mr. Trump told the CBNC that he was "not happy" with the Fed's tightening.

Historically, U.S. presidents have been circumspect about commenting on the Fed's actions in deference to the central bank's political independence. Although some presidents have sought to exert influence over Fed decisions in various ways, that autonomy is generally regarded as important for insulating monetary policy from undue political pressure.

But Mr. Trump has seen fit to break that protocol.

"These types of comments could be perceived to threaten the autonomy of the Federal Reserve," Lindsey Piegza, chief economist at Stifel, told CNBC.

Powell is expected to address monetary policy in a changing economy in a speech Friday in Jackson Hole, Wyoming.

While Mr. Trump may complain, there's little he can do to prevent the Fed from continuing to raise rates, with two more hikes expected this year.

Yet the president does have authority to nominate members to the Fed's board of governors and to remove governors for "cause," although that is rare. The last time a Fed chair was removed from his position was in 1979 under the Carter administration.