The Red Devils are currently eight points off the pace set by the Gunners, having taken just five points from their opening four home games.
The recent Old Trafford loss to West Brom was followed on Saturday by a dull home draw against Southampton.
But Wenger believes it is far too early to rule United out of the Premier League race.
The Frenchman said: "It is too early. They are not out of the title race.
"Are Man United out of the title race? No. You cannot rule Man United out today.
"They have big players, big experience and they are a big club.
"The gap is three games basically that is very quick in our league."
Wenger was delighted with the performance of his Arsenal side in the 4-1 victory over Norwich, adding: "We had periods where we were absolutely outstanding, but periods where we suffered as well because Norwich were good. They worked very hard and are a good side.
"We took advantage of them getting tired in the last 20 minutes in a very clinical way, and their goalkeeper made some fantastic saves."
Arsenal's own title credentials will be further tested as they face Liverpool and Manchester United in two of their next three league games, but Aaron Ramsey is confident they can sustain a challenge.
Ramsey said: "That's what we'll be looking to do. We're top of the league at the moment and that's where we want to stay.
"They are the games that every player wants to play in, you want to test yourself against the best. These sort of games are fantastic to play in and I'm sure we'll be looking forward to those games.
"One of the biggest things was the start of the season. We've had to play catch up in recent years and hopefully we can continue to build on this and stay strong until well after Christmas."
Wenger has a wealth of options in midfield, with the return to match fitness of Santi Cazorla following an ankle injuring meaning Ramsey could be rested to the bench against Norwich on Saturday.
The Wales international replaced Mathieu Flamini just before half-time after the French midfielder suffered double vision following a clash of heads with Alex Tettey and is now a doubt for Tuesday night's Champions League game against Borussia Dortmund as a result.
Wenger knows he will need to fully utilise the group if Arsenal are to mount a sustained push for honours in 2014.
"We have a squad that is, number and quality wise, very, very good. After that in January we are not desperate (to buy) now," the Arsenal boss said.
"If there is a good opportunity (to buy), why not? But if you know who is out injured now, they will come back in November, the beginning of December, then you have a really massive squad."
Wenger added: "With the number of competitions involved, everybody thinks they have a chance to play. That is what is the most important.
"As long as you fight for things, everybody keeps the focus."