WASHINGTON—President Barack Obama pressed financial regulators Monday to complete post-financial crisis rules aimed at protecting the financial system against future shocks.

Mr. Obama "stressed the need to expeditiously finish implementing the critical remaining portions of Wall Street reform to ensure we are able to prevent the type of financial harm that led to the Great Recession from ever happening again," according to a White House statement after the meeting.

Regulators have been slowed by industry lobbying, agency disagreements, budget constraints and legal challenges. Just 38.9% of the rules required by the 2010 Dodd-Frank financial law—many of which were supposed to be in place by July 2012—were finished by July 1, according to law firm Davis Polk & Wardwell LLP, and more than 60% of the law's deadlines for rules have been missed.

Republican critics say the slow progress is evidence that the Dodd-Frank law is flawed. "Dodd-Frank is an incomprehensively complex piece of legislation that is harmful to our floundering economy and in dire need of repeal," said Rep. Jeb Hensarling (R., Texas).

Judd Gregg and Kenneth Bentsen, who head the Securities Industry and Financial Markets Association, Wall Street's largest lobbying group, said in a statement that regulators should "focus on getting the remaining rules done right because poorly written rules could harm our strong capital markets that support a strong economy and help Main Street Americans succeed."