He acknowledged that if inflation ran “persistently below” its target, that would be an “issue” the Fed would have to address.

Mr. Powell’s decision to dismiss the slowdown in inflation as fleeting — without detailing how the Fed will react if price gains stay low — may have been an effort to convince investors that the Fed is happy to hold rates steady for now.

Many investors had begun to expect a rate cut later this year, and stock prices fell after the Fed news conference.

“The market was pricing in nothing but rate cuts,” said Gennadiy Goldberg, United States rates strategist at TD Securities. “I think he was trying to push back against the idea that the economy is turning lower and the Fed can never generate inflation.”

But economists said there was no reason for the Fed to move now, given the state of the economy.

“Inflation is low and the economy is fine, and given that combination of factors, there’s really nothing for the Fed to do here,” said Ellen Zentner, the chief United States economist at Morgan Stanley. “The best prescription right now is for them to stand by, stand pat.”

Congress has given the Fed two jobs: maintaining full employment and achieving low, stable inflation. But officials have not sustainably hit their 2 percent target since formally adopting it in 2012. If it lingers too far below that goal for an extended period, consumers and businesses could come to expect permanently slower gains, making it harder for the Fed to ever coax inflation higher.

“I do think it’s important that inflation run close to, and sustainably, for a sustained period of time, and symmetrically around 2 percent,” Mr. Powell said on Wednesday. Otherwise, lower inflation expectations could “put downward pressure on inflation and make it harder for us to react to downturns and harder for us to support the economy in difficult times.”