Moscon, who has been a key domestique in a successful first two weeks of the Tour for the team that has seen Geraint Thomas take the race lead and Chris Froome sit in second, was 28th across the line on the stage, but was later disqualified by the race organisers.
The disqualification is a result of an altercation with young French rider Elie Gesbert (Fortuneo-Samsic) which occurred just 800m into Sunday's 181.5km stage through south-west France, where the Fortuneo-Samsic team say that Gesbert was "punched" by Moscon.
"800m after the start of the 15th stage, Elie Gesbert received a punch from Gianni Moscon. After viewing the images, the race jury decided to exclude the rider from Team Sky of the Tour de France," a tweet from the team read.
Video footage of the incident shows Moscon taking a swipe at Gesbert with his right arm before launching in acceleration in pursuit of Gesbert's team leader Warren Barguil who had attacked a few seconds previously.
In its decision the race jury referred to article 12.1.040.30.1 of the UCI regulations, an "act of violence among riders" that can result in a fine or "disqualification for particularly serious aggression."
Responding to Moscon's disqualification, Team Sky principal Dave Brailsford said, "We support and accept the decision by the race organisers to exclude Gianni Moscon from the Tour de France.
"Gianni is desperately disappointed in his behaviour and knows that he has let himself, the Team and the race down.We will address this incident with Gianni once the Tour is complete and decide then if any further action should be taken."
Thomas will have to continue through the remaining stages, including three days in the Pyrenees, without one of his key domestiques, with Team Sky down to seven riders. Pyrenean stages to come without one of his helpers. Team Sky now counts seven instead of its original eight-man team.
It continues a string of problems for the 24-year-old Italian. In June, the UCI disciplinary commission cleared him of hitting Sébastien Reichenbach during the 2017 Tre Valli Varesine, with Reichenbach saying that Moscon caused him to crash.
That case came after another with Reichenbach's former Groupama-FDJ team-mate Kévin Reza, where Moscon was reported to have used racial slurs against the black French rider.
Team Sky sidelined Moscon for six weeks and sent him on a diversity awareness course after that incident.
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