Reed was punished for administering a hit to the head and neck area of Pittsburgh wide receiver Emmanuel Sanders in a Sunday night loss to the Steelers. Reed was given unnecessary roughness penalty on the play.
It is the second time this season and third in three years that Reed has been found to have hit a player deemed to be defenseless.
He was fined $21,000 for hitting New England receiver Deion Branch during a Sept. 23 game and $10,000 fine for a blow to New Orleans quarterback Drew Brees in December 2010.
"We cannot tolerate repeated violations of rules, especially rules related to player safety," said Ray Anderson, the NFL's executive vice president of football operations. "We will continue to take the strongest possible action to deter these types of violations and protect our players."
Reed, an 11-year veteran, is not allowed to practice or play in Baltimore's next game Sunday against San Diego