NEW YORK (Reuters) - A JPMorgan Chase ( JPM ) executive told thousands of employees he wanted "more hustle" days after the bank's CEO Jamie Dimon scorned staff pushback against its five-day return-to-office policy.

The memo illustrates the tension between JPMorgan's ( JPM ) emphasis on in-office culture and employees who cite its strong performance while flexible working policies were in place.

"We need more hustle and scrappiness," Rohan Amin, chief product officer of the Chase consumer business, wrote in a memo to more than 25,000 employees last week. He cited a call for feedback on artificial intelligence that prompted fewer than five responses, and gave another example in which internal bureaucracy blocked better results.

Some employees balked at Amin's criticism, according to two sources who declined to be identified discussing personnel matters. By contrast, another source said Amin received an influx of productive feedback in response to the latest memo.

"There's a lot happening--return to office adjustments, open questions, real estate challenges," Amin wrote. "I also know that uncertainty can be frustrating... That said, I have to ask: where's the hustle?"

Separately, Dimon told CNBC on Monday that he respects employees who don't want to come into the office five days a week, but said the policy will not change because it is best for clients and the company.

"I am not against working from home, I am against where it doesn't work," he said, adding that 10% of the bank's jobs are done remotely.

Some employees have sought advice from the Communications Workers of America on how they might set up a labor union, a rare thing in the U.S. finance sector. The petition has received 1,200 signatures, Dimon told CNBC.

When asked about the in-person work policy during the a staff meeting earlier this month, Reuters reported exclusively on Dimon's response: "Don't waste time on it. I don't care how many people sign that fucking petition," he said at the time.

On Monday, Dimon told CNBC that he shouldn't swear in town hall meetings.