Frank was referring mainly to the proposal, announced by Obama earlier on Thursday, that would prevent banks or financial institutions that own banks from owning, investing in or sponsoring a hedge fund or private equity fund.
Frank said any mandate to make banks sell hedge funds or private equity immediately would be a mistake.
"I will be supportive of this with no less than three, maybe five years before it's done," he added. "To order this to be all done all at once, it would be a fire sale and I would be opposed to that happening."
However, Frank said he was not opposed to an immediate curb on proprietary trading, in which banks make bets on financial markets with their own money, rather than executing a trade for a client.
Frank said the financial regulatory reform bill that the House had already passed would simply allow regulators to curb bank practices without requiring them to do so. To mandate those changes, he said, that bill would have to be amended.
The legislation is awaiting action in the Senate.