Separately, China UnionPay, the mainland's largest bank-card issuer, said in a statement, initially cited by Reuters, that it had not changed its policy on overseas withdrawal limits for mainland-issued cards, which were set at 10,000 yuan ($1,449) a day.

The reaction for shares of listed casino companies was stark. Wynn Macau fell 7.8 percent, Sands China dropped 6.4 percent, Melco International plunged 8.79 percent and Galaxy shed 6.37 percent by 11:44 a.m. HK/SIN. That followed losses of as much as 10 percent in their U.S.-listed counterparts overnight.

Alex Bumazhny, senior director of gaming, lodging and leisure at Fitch Ratings, told CNBC's "Squawk Box" on Friday that it would be hard to determine how casinos would be impacted by the restrictions.

While he noted that the government has previously issued other restrictions on UnionPay machines, it would be difficult to parse the hit from the new measures from other factors affecting the market, such as the mainland's corruption crackdown and its general economic fundamentals.

He added that players have managed to work around previous restrictions as well.