Sanchez has scored just once in 10 appearances for United since making the move to the 20-time English champions during the January transfer window.
United are reportedly 'concerned' about the poor form of the 29-year-old, but Cole has backed the attacker to 'turn it around' in the final weeks of the 2017-18 campaign.
"Alexis Sanchez is a superb player," Cole told Goal.com. "I think sometimes when you try too hard to impress, to give too much, sometimes it goes against you.
"Arsenal play a different way to United however you look at it. You have got to consider those factors when you look at it. The lad is playing the same way he did at Arsenal even though United are playing a different way but I'm sure it will turn around for him."