The rainbow jersey wearer collided with Maxime Vantomme (WB Veranclassic-Aqua Protect) on his left when reacting in the group behind Greg Van Avermaet's attack.
He wrote on Twitter in response to the criticism, "I just saw the video of the contact with @MaximeVantomme at @GentWevelgem. I wasn't aware of it. I'm sorry but these things happen in races."
The incident occurred on the final ascent of the Kemmelberg with 34 kilometres to race. Sagan moved around a Quick Step cyclist but gave Vantomme a hard shoulder to move him out of his way.
"That's the life of a small cyclist," Vantomme responded on Twitter.
Others see it differently, however. They took aim at the Slovakian world champion, who is racing to defend his Tour of Flanders title this coming Sunday.
"I saw it and thought I had not seen it properly. I then watched the footage again and that's not nice. If it was me, he would have broken a rib, for sure. I would have pushed back."
The show also featured Dutch professional Bram Tankink (LottoNL-Jumbo), who said Sagan, as one of the biggest stars in world cycling, is throwing his weight around in the peloton.
Watch: Tour of Flanders essential guide
"Sagan is twice world champion, he wears that rainbow jersey and thinks he can pass anywhere, then runs a boy from a small team over," added Tankink. “It doesn't end."
Naesen placed 22nd on Sunday, Tankink 35th. Sagan finished third after some negative racing or what Sagan called "cheap games", where Niki Terpstra (Quick Step Floors) stopped pedalling and opened a gap for the winning duo to ride clear.
The Kemmelberg images only surfaced overnight. The UCI jury fined cyclists in Tuesday's Three Days of De Panne for riding on pavements, but has not taken action for Sagan's move.
The Tour of Flanders takes place on Sunday, with Sagan and Van Avermaet joint-favourites for victory.
Thank you for reading 20 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1