SAN FRANCISCO — When the virtual currency markets were hot last year, the boxer Floyd Mayweather Jr. and the music producer and rapper Khaled Khaled, known as DJ Khaled, were getting paid to promote new digital tokens.

On Thursday, regulators announced that Mr. Mayweather and Mr. Khaled will have to give back all the money they received for those promotions and pay additional fines in the latest crackdown on the virtual currency markets.

The Securities and Exchange Commission said Mr. Mayweather was paid $100,000 and Mr. Khaled $50,000 to promote a virtual currency released last year by the start-up Centra Tech in a so-called initial coin offering. The men did not disclose those payments in their online postings hyping the digital coin, the regulators said.

The payments and broader problems with the Centra coin offering were first reported by The New York Times last fall.