He says the GOP's promised repeal of the law would mean the return of a financial system whose near-collapse led to the worst recession since the Depression.
"Without sound oversight and commonsense protections for consumers, the whole economy is put in jeopardy," Mr. Obama said Saturday in his weekly radio and Internet address. "That doesn't serve Main Street. That doesn't serve Wall Street. That doesn't serve anyone."
The law passed despite nearly unanimous Republican opposition. It sought to rein in a financial system that had sped ahead of outdated rules, allowing banks, traders and others to take increased risks.
It limits bank overdraft fees and ends abuses such as retroactive interest rate increases on credit card balances.
It came in the wake of a $700 billion bank rescue passed in the final months of George W. Bush's presidency. While the bailout is credited with providing stability, it's deeply unpopular with voters angry of taxpayer money being used to help prop up huge banks.
President Obama promised that the measure ensures that taxpayers will "never again be on the hook for a bailout."
Mr. Obama's address came less than two weeks before elections in which Republicans have a good chance of taking over the House, if not the Senate. The financial regulation measure hasn't been a central campaign issue.
House GOP leader John Boehner of Ohio has called for a repeal, as have top Senate Republicans. But President Obama still would stand in the way through his veto power.
In the GOP's weekly message, Sen. John Thune of South Dakota denounced President Obama's economic stimulus bill, overhaul of the health care system and plans to allow Bush-era tax cuts for wealthier people to expire.
"We have learned the lessons not only of what hasn't worked over the past two years, but what didn't work the last time Republicans controlled Congress," Thune said. "We are determined to take this country in the right direction."
Added Thune: "Are you better off today than you were two years ago?"
By Associated Press Writer Andrew Taylor