The Gunners' manager also dismissed suggestions that United, who face losing Keane at the end of the season, might buy the volatile French international as a replacement.
Wenger says he will be taking no action against his midfielder after studying the video of the incident in which Vieira thrust his head into Keane's face, having been kicked by the Irishman.
Wenger, who says he will continue to defend Vieira because of his belief that rivals often seek to ignite his short fuse, said: "The referee did well in that incident and just calmed everything down, which was the right thing to do. My feeling is that Beckham dived in front of the box to try to get a free-kick and after that, Keane came in from the back and Patrick was kicked.
"He got some bad tackles in that game and everybody is just after him. I believe I have to protect him from the media and all that stuff. It was the kind of incident that sometimes happens in the big games but Patrick was not the one who provoked it. And the most annoying thing is that sometimes he is the target and there is no real protection.
Asked about his reaction if Ferguson made a bid, Wenger said: "He will just have to like somebody else. I don't know why you ask me that question. If I asked to buy Beckham what do think United would say?"
Vieira will again be without his injured midfield partner Emmanuel Petit when Arsenal try to put aside the setback of losing to United when they face newly-promoted Bradford City at Highbury tonight.
Ferguson is making a bid to sign the goalkeeper Taibi Massimo from Venezia. The United manager has offered pounds 2.5m for the experienced 29-year-old Sicilian following injuries to Mark Bosnich and his Dutch stand-in, Raimond van der Gouw.
Bosnich is out with a hamstring injury that should heal in a month. His form, particularly his kicking, has worried United since he signed, however. Ferguson would also like midfield cover and is interested in Milan's Thomas Helveg.
Steve Harkness is taking a pay cut to sign for Blackburn Rovers. Harkness met Rovers to negotiate terms yesterday and is willing to come down from his pounds 900,000-a-year contract at Benfica. Blackburn are only ready to pay Harkness around half that figure, but the defender is poised to accept and sign today.
The move to Portugal has not worked out for the former Liverpool left- back, who moved to Lisbon earlier this year. Harkness was left out when manager Graeme Souness left and then became involved in a row with the club president that saw him banished from the squad.
The deal, Kidd's 12th signing, is a sign of support for the manager despite a disastrous start to the season. The pounds 500,000 transfer is one of his smallest.
The Charlton manager, Alan Curbishley, has made an offer for Dunfermline's Greg Shields in a pounds 700,000 deal to solve his problem at right- back. Curbishley is tying up personal terms with the former Rangers prospect.
Sunderland have completed the signing of French midfielder Eric Roy from Marseilles. Roy, 31, who has signed a two-year deal, played for Marseilles for more than eight years and played at the Stadium of Light when he was on trial last month in Kevin Ball's testimonial match with Sampdoria.
Sunderland's manager Peter Reid said: "He is an experienced player - an elegant midfielder who will be a great addition to the squad."Reuse content