Lewis, 21, endured the slurs as the Bairns suffered a chastening 4-2 defeat in the Scottish Cup against local rivals Stenhousemuir on Saturday.
A swift statement from the Championship club confirmed the complaint, stating “we wholeheartedly condemn the abuse received by Dennon and will work to identify those responsible”.
McKinnon had a heart-to-heart with Lewis on Monday morning and revealed the young attacker has been deeply effected by the incident.
“He is very, very upset by it all,” McKinnon said. “He was devastated and I’m just glad he came forward and said something. It’s never nice to watch someone go through something like that. It’s totally unacceptable and we don’t want to see that happen to any player.
“Dennon will get all the support he needs. He was in speaking to us about it on Monday and we’ll do everything we can to help him through this.
“We don’t need that in football, there’s just no excuse for it and I’m delighted the club have been so pro-active in making a statement.”
Lewis, who has scored two goals in 19 appearances since making the move north, is living away from home for the first time after joining Falkirk from Watford last summer, exacerbating a tumultuous few days for the attacker. And McKinnon concedes he may be in no frame of mind to feature in their upcoming Championship fixture against Inverness on Saturday.
“Whether he’ll be in the right frame of mind to play at the weekend is something we’ll just need to manage,” he acknowledged. “We’d like him to be, but Dennon’s going through quite an experience.
“We are talking about a young kid away from home on his own – up all the way from England – and it’s not nice for him. He’s struggled with it and we’ll give him all the time he needs. If he’s not available on Saturday, we’ll get on with things.”
Lewis himself took to social media yesterday and said that the vile taunts he had been subjected to “crossed a line”.
“I have never gone through a period like this in my life,” he said in a statement posted on Twitter. “From a footballing standpoint things are not going as planned for anyone involved at the club. From a personal standpoint, never in a million years would I have expected to be subject to racial abuse from Falkirk fans.
“I understand the frustration and anger. As a lover of football myself, all you want to see is your club do well. However, for me this is a line crossed and the abuse is disgusting.
“Whilst the future is unclear at this moment in time I am still a Falkirk player and will try to do my best for the team and support everyone involved with the club.
“I appreciate the messages received and I know this doesn’t embody the Falkirk fans in its entirety. Please understand where I am coming from with this message and know that I will not and cannot stand for this.”