Jamie Dimon, the chairman and CEO of JPMorgan Chase, issued a warning Friday to rivals in the custody and cash management businesses: "We're not backing out."

Dimon said competitors had been spreading rumors that the New York bank was getting out of the field.

"Some of your salespeople are saying, 'JPMorgan is getting out and you shouldn't give them business,' " Dimon said. "So it kind of irritates me a little bit."

His remarks at the Barclays Global Financial Services Conference in New York were part of a wide-ranging 40-minute question-and-answer session that covered topics as diverse as Bitcoin and China.

His most pointed comments were directed specifically at rival bankers in the audience.

"I do want to make one point because some of you, you all work at competitors, we are in custody and cash management," he said. "We love the business. We put some of our best people in those businesses to run it. We intend to win in custody and cash management. Watch that space. We're not backing out."

Dimon implied that some of the rumors related to a change in leadership in the custody and cash management business. In June, JPMorgan named Teresa Heitsenrether global head of custody and fund services, replacing Nick Rudenstine, who remains at the bank. Heitsenrether, one of the most senior women at JPMorgan's investment bank, had been the global head of prime services.

On another topic, Dimon expressed tentative curiosity about the blockchain — the record-keeping technology that powers the Bitcoin network.

While reiterating his view that Bitcoin cannot succeed as a currency since governments won't tolerate money they cannot control, Dimon said JPMorgan is studying the potential for blockchains to track ownership of financial assets such as loans.

The bank is trying to figure out whether decentralized electronic ledgers can do the job more efficiently than longstanding industry utilities like the Depository Trust and Clearing Corp., he said.

"If it's more efficient we should do it," Dimon said. "And I don't know yet. It's got to be secure."

The bank has met with former JPMorgan executive Blythe Masters, who now runs a startup called Digital Asset Holdings, and with "a bunch of these other blockchain companies," he said. "We have a study group on this whole thing. … And I think most of the banks do at this point."

Dimon also had bullish comments about China, calling the global stock market plunge in July, a reaction to the slowdown in the world's largest economy, "a speed bump" and "not that big a deal."

"Our view of China is in 20 years it will be a large, developed nation probably housing 20% to 25% of the global Fortune 2000 or something, and that's what we're keeping our eye on," he told investors.

The recent market woes "reminded the world that China is going to be maybe a little more volatile than you think," he said.

When asked about the Federal Reserve's decision this week not to raise interest rates, Dimon called the discussion about a potential 25-basis-point increase "a lot of chatter about nothing." But he did express some concern that when rates do rise, it may catch some off guard.

"I also think one day [rates] will rise faster than people think, not slower," he said.

Dimon reiterated that he will no longer be on every quarterly earnings conference call, though he may end up doing two or three a year. He said he feels confident that JPMorgan Chase's CFO, Marianne Lake, can handle the job.

He also said that every time he is asked about a retirement date, "I'm going to say five years."

He even admitted, "I don't want to retire."

"As long as the board wants me and I can still do the job and I have my health and stuff like that and I want to work hard," he will keep going, he said. "I think when I can no longer work hard I should leave this stuff."

Dimon, 59, was diagnosed last year with curable throat cancer. His treatment was successful.