A goalless draw at Wigan on Sunday was the third successive league match the Gunners had been held and their lead at the top is just two points.
United, because of their FA Cup action at the weekend, have a match in hand and currently look the side most capable of finishing strongest.
In contrast, the formerly free-scoring Arsenal have seen their goals dry up with three in their last three drawn games.
"I am sure we will take off again. We have gone through a difficult patch. We have to keep our calm and focus and belief," he said.
"Four points (have been) dropped in the last three league games. Against Aston Villa a point was just what we deserved but Birmingham and Wigan were four points dropped.
"You go through a patch like that and the negative is a deficit in points. The positive is we didn't lose a game but there was room for us to take more than that.
"But I am very confident we still have good chances to do it (win the league)."
Arsenal face another relegation-threatened side in Middlesbrough at the Emirates next weekend, and Wenger is looking for his side to lift themselves out of their current dip against Gareth Southgate's team.
"You keep calm, focused, determined, and you go from game to game and give everything," he added.
"We want now to come back to winning habits straight away next Saturday. I am still very confident."