Le Bourg-d'Oisans - Tour de France director Christian Prudhomme has demanded fans show more respect a day after Team Sky were booed off the podium and Vincenzo Nibali crashed out when his bike got tangled up.
He hinted there could be measures to stop fans running behind riders during the spectacular mountain stages that attract thousands to the roadside.
"They have only one wish, to be on television and take a selfie," Prudhomme told AFP prior to the 13th stage from Bourg d'Oisans to Valence.
"We have no wish to see that again."
He added: "Rocket flares don't belong on bike races. They make the riders breathe in noxious air, and they blind them.
"It just doesn't make sense."
Sky's domination so far has seen Geraint Thomas win two key alpine stages in succession to lead the race by 1min 39sec from teammate and four-time champion Chris Froome.
But their success is doing little to appease detractors.
Thomas was booed and jeered as he crossed the finish line on Thursday, then while he stood on the podium.
Earlier in the stage, a bag or camera strap got entangled with Nibali's bike, sending the Italian, riding through a plume of smoke, crashing to the ground and on his way home after he suffered a fractured back.
Froome, who was reportedly spat at, also received a hearty slap on the back from an over-zealous fan.
Although Tour chiefs have improved conditions for the peloton in recent years by limiting the sale of alcohol and having police motorbikes clear a path for the riders, Prudhomme said: "The climb up the Alpe d'Huez was painful.
"The riders of the Tour, the champions of this race, need to be respected."
Sky have won five of the past six editions of the Tour, Bradley Wiggins beginning their impressive streak in 2012 and Froome winning in 2013 and then 2015-2017.
The Kenyan-born racer is targeting a seventh Grand Tour success, and, if successful, would become the first cyclist since deceased Italian climbing great Marco Pantani, in 1998, to win the Giro d'Italia and the Tour in the same year.
Froome was only cleared to compete days before the start by the International Cycling Union (UCI).
For months, the Briton was embroiled in controversy after a sample from the 2017 Tour of Spain revealed twice the permitted amount of the asthma drug salbutamol in his system.
Froome and Team Sky were booed on the podium at the start of the Tour in the Vendee.
Prudhomme said: "I heard the whistles on Alpe d'Huez, just as I did in the Vende.
"On the roadside it's been calm for the past 10 days or so, with very few anti-Sky or anti-Froome banners.
"But suddenly, we've seen a lot more. All I can do is renew calls for calm, for good sense and for serenity with regard to the riders on the Tour de France.
"Don't whistle and, obviously, don't touch the riders. Even if it's just an over-friendly backslap."
Prudhomme added: "The vast majority of the fans on the roadside are well-meaning.
"But yesterday, on the second half of the climb the public were at times a little reckless.
"Even though it wasn't an overexcited spectator who brought Nibali down, it was a spectator, not a police motorbike."
Prudhomme added: "We want the Tour public to be the same as they always have been.
In 1975 Belgian legend Eddy Merckx was famously forced to abandon after being punched by one fan.
"If we really want to see things overspill on the Tour, we have to look all the way back to 1975 and Eddy Merckx."