Wenger loses appeal against European ban
Wenger was suspended for breaking the conditions of a previous ban he served during the Champions League play-off tie at home to Udinese.
Although banned from communicating with his team, Wenger sat in the stands at Emirates Stadium and was in contact with his players over a mobile telephone.
Wenger, who will miss Arsenal's group games against Borussia Dortmund and Olympiakos, said the rules were confusing.
The original ban was imposed for his behaviour during last season's tie at Barcelona.
Arsenal have also been fined 10,000 euros for "improper conduct by their officials," UEFA said.