The Federal Reserve's approval of the Volcker Rule, meant to rein in risky trading in reaction to the financial crisis, sends a clear signal, bank analyst Mike Mayo of CLSA said Tuesday.

"Banks need to be pillars of strength of stability. They need to facilitate the economy. They need to be a port in the storm," he said. "But no, they can't have a casino inside the bank, so from that standpoint, bank CEOs are put on notice."

(Read more: What you need to know about the Volcker Rule)

Mayor tol CNBC's "Halftime Report" that although banks might find loopholes to circumvent some of the rule's provisions, it would provide accountability in the long term.

"I think if after the fact you have a big loss, banks don't get off so easily," he said.

The financial industry has "to some degree" already adjusted to the rule's requirements, Mayo said, adding that he is confident his top bank stock will not be affected negatively.

"The Volcker Rule is not a game changer for Morgan Stanley," he said. "I'm not the least bit worried Morgan Stanley hasn't adjusted."

Mayo holds long positions in Morgan Stanley, JPMorgan, Citigroup, KeyCorp and State Street.

—By CNBC's Bruno J. Navarro. Follow him on Twitter @Bruno_J_Navarro.