Per the official site:
"A misrepresentative article by Dan Roan, which has since been modified, appeared on the BBC's website a short time later which omitted significant comments of clarification and took the interview completely out of context. Manchester City promotes a positive and welcoming approach to media outlets, however it is felt, in the absence of any correction or apology that there is no option but to issue an immediate ban to Dan Roan from future media activity."
It was this article that appeared on the BBC's website that offence was taken to as City felt that comments made by Vieira were not representative of the full interview.
Vieira has of course made headlines recently with comments regarding Manchester United's decision to bring Paul Scholes out of retirement; citing it is a weakness with their squad, comments that drew a swift response from Sir Alex Ferguson (amongst others) to re-ignite the whole discussion around the relevance of 'mind-games' and help intensify the focus of the media even further.
Welcome to the title run-in.