The team did not say how Haley was injured, but NFL Network reported he injured his hip in an altercation at a bar.
According to the report, Haley was pushed outside a bar near Heinz Field on Sunday night following the Steelers' victory over the Browns.
Because of the injury, Haley may coach Pittsburgh's Jan. 14 game from the booth instead of the sidelines as he usually does. The Steelers have time to figure it out, because they have a bye this weekend.
Bob Pompeani of KDKA-TV in Pittsburgh reported that Haley will return to his office at team headquarters this week.
Police reportedly investigated the incident but no arrests were made.