United lost to Barca in the 2009 final and are out for revenge on English turf.
"There will be no surprises because they haven't changed their style in years but they will be a tough prospect and definitely the favourites in the final," the Serbia centre-back told Belgarde's B92 television website.
"Maybe we have a little bit of an advantage in logistics because we are closer to the venue, but we know that their fans will turn up in numbers just like our own."
Vidic, who scored in Sunday's 2-1 win over Chelsea which all but secured United the Premier League title, said his side were still completely focused on a record 19th domestic crown.
"We haven't had time to think about Barcelona yet because we have to concentrate on our next game away to Blackburn and make mathematically sure that we've won it," he said.
"Only when we have done that can we turn our attention to Barcelona, I've seen them several times this season including their semi-final tie against Real Madrid."
United, who are six points ahead of Chelsea with two matches left in the Premier League, need only one point from their last two games against Blackburn and at home to Blackpool to secure their 12th league title under manager Sir Alex Ferguson.
Vidic, who was named captain this season, revealed anxiety had crept into United's dressing room after Chelsea were able to cut a 15-point deficit with nine wins in 10 games prior to their visit to Old Trafford.
"The pressure was immense after they whittled down our big advantage to just three points before the showdown, but it makes the victory that much sweeter because we are on the verge of winning the title after beating our closest rivals," he said.
"It means a lot to me that I scored but the team comes first and the most important thing is that we are now in a commanding position to cross the finish line first.
"As the team's captain I just try to do the same things I've always done and be at my best all the time, because being the United captain is a great honour and I know I have to repay the faith vested in me by the club.
