Grealish appeared to be shown slumped in the street during a holiday in Tenerife in an image posted on Twitter.
The player himself appeared to laugh off the claims via his Twitter account and former Villa player Staunton, who had two spells with the club during his career, admitted social media makes it hard for modern players to keep out of the public eye.
“With mobile phones you are not going to get away with anything, it is a downside to the modern day player,” Staunton told Sky Sports News HQ.
“They have to grow up even quicker. He’s only a young lad and I am not condoning what he has done but he is young and needs to get a lot out of his system. You just hope it’s a one-off rather than a recurrence of things.”
Grealish found himself in trouble last year when manager Tim Sherwood warned the 19-year-old about his conduct after he appeared to be filmed inhaling legal high nitrous oxide.
Staunton has urged him to focus on his game as he looks to build on some impressive performances last season.
“A few good games at the back end of a season doesn’t mean you are a player,” added Staunton.
“He has a tough season ahead of him next year and the one after. When he has played 50-100 games, then we will see the real Jack Grealish.”