WASHINGTON—The federal government has put Wells Fargo & Co. on a much tighter leash, requiring the firm’s banking unit to seek approval before making a wide range of business decisions, after a regulator revoked key portions of a two-month-old settlement in the company’s sales scandal.

The announcement late Friday caught Wells Fargo executives by surprise and injects regulators far deeper into the bank’s operations. The bank is now banned from offering departing executives “golden parachute” payments, according to the statement from the Office of the Comptroller of the Currency, and it must get the OCC’s permission before it changes its business plans, hires or fires senior executives, or revamps its board of directors.

The OCC, in the terse one-paragraph statement, didn’t explain why it had unilaterally altered the terms of the September agreement negotiated with Wells Fargo, which included a $185 million settlement over the opening as many as 2.1 million accounts using fictitious or unauthorized customer information. An OCC spokesman declined to elaborate beyond the statement.

“I’ve never seen anything like this,” said a former OCC official who asked not to be identified. “It’s surprising to see the agency reverse themselves on a negotiated agreement without some new information coming to light.”

In the wake of the sales scandal, CEO John Stumpf retired, and the bank’s new leader, Timothy Sloan, has been trying to persuade government officials and politicians that the company has been working diligently to correct the problems. Mr. Sloan most recently spread that message during a series of meetings in Washington, D.C., earlier in the week.