The 21-year-old raised his middle finger to City fans in his side's 6-3 defeat to Manuel Pellegrini's men on Saturday, and had admitted the charge of making an offensive gesture, but appealed against the mandatory two-match ban.
However, an independent regulatory commision has upheld the suspension and Wilshere will now miss the home clash against Chelsea on Monday and the trip to West Ham on Boxing Day.
An FA statement read: "Arsenal’s Jack Wilshere has been suspended for two matches by an Independent Regulatory Commission.
"Wilshere was charged by The FA with making an offensive and/or insulting and/or abusive gesture during the fixture between Manchester City and Arsenal at the Etihad Stadium on Saturday 14 December. The incident was not seen by match officials but was caught on video.
"Whilst admitting the charge, Wilshere claimed the standard sanction for this offence was clearly excessive. The Commission rejected this claim and the two match suspension will commence with immediate effect."
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