A drop in customers buying cryptocurrencies with credit cards slightly dampened Mastercard's quarterly growth, the company said on an earnings call this week.

While cross-border volumes grew by 19 percent, that number dropped by 2 percentage points from the fourth quarter, in part because fewer people bought digital currencies like bitcoin with their credit cards.

"This is due to the recent drop-off in crypto wallet funding," Mastercard chief financial officer Martina Hund-Mejean said on the earnings call Wednesday. "We expect cross-border growth to moderate somewhat."

Customers can use Mastercard to buy in and out of cryptocurrencies, and store them into what's known as "crypto wallet." But some banks have prohibited the practice.

Bank of America, JPMorgan Chase and Citigroup are among those that banned credit card purchases for digital currency in February, citing price volatility and potential credit risks.

Mastercard's CEO pointed to uncertainty in Asia, and said some exchanges are pulling back in South Korea, while others in Japan are worried about security.