The ASA upheld a complaint arguing that Nintendo oversold the Wii U's dual-screen functionality in its first wave of UK adverts, reports CVG.
The advert appears to suggest that the ability to switch gameplay to the GamePad controller would be available on all games.
Denying the claims, Nintendo said that there was "nothing in the ad that implied all featured functions would be available on all games, as this would be entirely dependent on the games' publishers and not the console manufacturer".
However, the ASA decided to uphold the complaint and has subsequently banned Nintendo from broadcasting the advert in its current form.
"The ad referred to a number of features of the Wii U console and GamePad, including being able to shoot at the TV using the GamePad, switching gameplay to the GamePad if someone else wanted to use the TV and using the GamePad to zoom in on targets, enter key codes and interact with the surroundings in the game," reads the ASA report.
"The ASA considered that it would be clear to consumers that many of these features would not be available in all games.
"However, we considered that the option to switch gameplay to the GamePad controller could be available on all games, and as this was a new console consumers would not have an awareness of whether this was something specific to individual games or a general feature of the console.
"We considered that, in this context, the ad should have made clear that this feature would not be available on all games. Because it did not, we concluded the ad was misleading."
Nintendo recently confirmed that the Virtual Console will be making its way to the Wii U soon, promising standalone GamePad support.
Wii U users can currently access Virtual Console content on Nintendo's new device by transferring files from the Wii and switching to a Wii Remote.
Watch Digital Spy go hands-on with the Wii U below: