"Other countries are affected as well," a Daimler spokesman told news agency AFP.
A problem with the steering system's pump could lead to a loss of fluid and "owners may not have sufficient control of the vehicle in areas, such as parking lots, where maximum power steering is required, increasing the risk of a vehicle crash," the NHTSA said on its website.
The Daimler spokesman stressed that drivers retained control of the car even in the event of a power steering failure.
Mercedes planned to fix the problem in 2010 and 2011 models this month by re-tightening a faulty fitting, the NHTSA website said.
Auto recalls have increased this year since the world's biggest car maker, Toyota, had to pay a record $16.4 million to settle claims it hid gas pedal defects blamed for more than 50 deaths in the United States.
On October 1, Daimler's German rival BMW said it would recall 350,800 high-powered BMW and Rolls-Royce autos worldwide because of brake problems that a BMW spokesman stressed were "without danger."