The British Board of Film Classification gave the film a 12A certificate but some cinemagoers said they felt it was unsuitable for viewers as young as 12, who were free to see it.
The BBFC's annual report reveals that although only 26 complained about the rating decision, it was still more than double the number who were unhappy about the next most controversial films - The Paperboy and The Wolverine, both of which saw 12 complaints raised.
Jack Reacher - based on the character created by British writer Jim Grant, who uses the pen name Lee Child - had already been subject to a number of cuts to get it down to the certificate it actually achieved.
Those who expressed concerns to the classification body said it was "too violent, dark and sadistic" for viewers aged 12, according to the report.
However, the BBFC affirmed: "The film is occasionally gritty and realistic, but the overall tone and treatment of the violence is similar to recent 12A action films such as the Bourne series."
The report outlines how changing attitudes in society have meant that some films have seen their certificates lowered when they have recently been re-submitted for reissued versions.
In the case of the French film Baise-Moi, one of the first films to feature real sex scenes to be given an 18 certificate, scenes which were cut in 2001 to achieve that level have now been restored for a 2013 DVD release.
The BBFC concluded: "Brief sight of sexual penetration during a rape scene was thought to heighten the sense of violation, encouraging viewer sympathy, rather than arousal."
However the hit comedy film Airplane! actually saw its certificate level changed to restrict its viewing. The report explained: "The film has been PG on video for over twenty years, but its moderate sex references, including the use of a blow-up doll, plus comic scenes of drug abuse, including cocaine snorting and glue sniffing, go beyond the BBFC's present classification guidelines at PG."
It went on to be given a 12A certificate.
The BBFC processed 1,042 films with a view to cinema release, the report said - the first time it has handled more than 1,000 since 1961.
The body's director David Cooke said: "The figures reflect the broader range of films being exhibited, an ever greater exploitation of digital screens, and the popularity of the BBFC's advice service."