BEIJING—Chinese central bank officials on Thursday offered a rare public defense after this week’s unexpected devaluation, saying the yuan will stabilize and eventually resume its climb.

At a news conference in Beijing on Thursday, People’s Bank of China Vice Gov. Yi Gang said China has the financial firepower to defend the currency as needed. But officials also said the yuan’s underpinning remains firm and that its value should strengthen, and dismissed the idea that the move was made to help the country’s sputtering exports sector.

“In the long run, the renminbi remains a strong currency,” said PBOC Assistant Gov. Zhang Xiaohui, using the other name for the Chinese currency.

 

They also said the move—made through a mechanism that they said was intended to give markets more say in how the yuan was valued—gives the central bank more room to maneuver at a time when the U.S. dollar is appreciating against most other currencies.

“A fixed exchange rate looks stable, but it hides accumulated problems,” Mr. Yi said.

On Thursday, traders pushed the yuan down as much as 0.9% from its previous close to 6.4470 against the dollar in early trade. After holding steady in the afternoon, the yuan gradually began to weaken again, as investors assessed Beijing’s latest commentary.

Much like the day before, China’s currency strengthened 0.2% in the last half-hour of trading on Thursday. A day earlier, people familiar with the matter told The Wall Street Journal that the central bank intervened in the currency markets in the final minutes of trading, forcing the currency up as the trading session closed for the day.

The yuan closed at 6.3990 Thursday, down 0.2% for the day. It has weakened almost 3% against the dollar since Monday, the day before the PBOC first devalued the currency.

The PBOC’s news conference was an unusual event for an organization that rarely puts forward a public face and typically communicates through lengthy messages on its website, sometimes posted well into the evening. Foreign reporters as well as state-controlled media were invited. It marks a rare public stepping out for Mr. Yi, the PBOC’s No. 2 official and the one responsible for day-to-day oversight of foreign exchange.

Mr. Yi described as “nonsense” a report that the PBOC wants to engineer an eventual 10% depreciation of the currency in an effort to help exporters, who play a significant role in the economy but have been suffering from sluggish global demand as well as a stronger currency. He also said China would continue on its own schedule to open the country up to freer cross-border capital flows despite recent market fluctuations.

Asked about the Wednesday move to intervene in the foreign-exchange market to defend the currency, Mr. Yi said the PBOC had stopped “regularly” intervening in the market to control the yuan’s value, but he said the central bank has adopted a “managed floating-rate regime” and would intervene during “external shocks.”

The central bank sets a daily rate for the currency against the U.S. dollar and allows trading in a limited band around it. The dollar has strengthened against most of the world’s other currencies in recent months, bringing the yuan with it.

On Tuesday, the central bank unveiled changes to the system that would give the market a greater role in determining that rate. The move gives the PBOC greater ability to act despite what the dollar does, even as it adds temporarily volatility, officials said.

“People have become used to a very stable exchange rate,” Mr. Yi said, but he said that stability “limits the independence of the central bank.”

Investors said that greater market influence presages more volatility to come. “It’s going to be a period of volatility for the next few months before [the yuan] finds its equilibrium level,” said Alexandra Edstein, senior portfolio manager at London-based hedge fund The Cambridge Strategy’s Asian currency fund. “The trend will be depreciation,” she said.

Earlier in the day, the central bank appeared to take into account Wednesday’s closing price when setting the yuan’s daily trading level. China allows the yuan to trade in a 2% band around its daily fix.

It set the yuan at 6.4010 against the U.S. dollar, down just 0.2% from the previous close and 1.1% weaker than Wednesday’s fixing. Still, that closing price reflected the late surge in the yuan after the intervention.