President Donald Trump is worried the Federal Reserve will raise interest rates two more times this year, a White House official told CNBC.

Aides to the president, however, are telling Trump the central bank is conducting policy properly.

Their message from Treasury Secretary Steven Mnuchin and National Economic Council Director Larry Kudlow is "the Fed is doing it right, let it happen. The sooner it happens, the sooner it will be over," said the aide, who spoke on condition of anonymity.

The central bank already has approved two increases this year. In June, officials indicated in their individual economic projections that there were two more increases in store before the end of 2018, likely in September and December.

Aides told Trump that they believe the Fed will stop when its target rate is around 2.5 percent. That would be well below the 3.4 percent that the Fed currently has indicated, according to projections issued in June. The current rate is targeted between 1.75 percent and 2 percent and sits at 1.91 percent.

Trump this week criticized the Fed and Chairman Jerome Powell for the increases adopted in March and June, saying that tightening monetary policy is threatening to thwart the economic recovery.

In an interview with CNBC, Trump said he was "not thrilled" that the Fed was raising rates and thus causing upward pressure on the dollar. In a tweet Friday morning, the president added that "tightening now hurts all that we have done."

The fed funds futures market, where traders bet on the Fed's moves in the months ahead, is indicating an 89 percent chance of a rate hike in September and a 63 percent chance of a December move.

An aide told CNBC that Trump understands that the Fed is independent and that he is merely expressing an opinion. The aide said Trump is being told by his confidantes that the central bank is moving properly and that it would be best to let monetary policy play out.

"He's not putting any pressure on them," the aide said, adding that the president realizes that Powell and several others are his appointees. "They're all his guys. It's his board."

Currency markets, however, reacted sharply to the president's Fed criticism.

The dollar index, which measures the U.S. currency against a basket of its global peers, fell 0.8 percent, on track for the worst performance in July. Longer-dated government bond yields rose on the day, with the 30-year bond crossing 3 percent for the first time since June 26. Response on the short end of the curve was more muted, with the 3-month bill down slightly and the 2-year yield rising modestly.

With reporting by Eamon Javers.