The Financial Services Roundtable, which represents dozens of banks and other financial services firms, said it was "very concerned" that adoption of the rules could impose "significant" and costly compliance burdens on banks.
"The statute and the proposed rule expand the role of financial institutions to police laws that are more appropriate for law enforcement agencies," the Roundtable said in public filings to the Treasury and Federal Reserve.
The criticism raises new questions about whether regulators will be able to enforce a law that, in effect, requires banks and other institutions to know the purpose and legality of payments in an industry - online gambling - in which federal and state rules often conflict.