Bastianini smacked into the back of his Ducati stablemate Zarco as they warmed up their brakes on the way to their grid slots just before the start of Sunday’s 23-lap Mugello race.
The Avintia rider was unable to take the start as a result, while Zarco had to complete the race with some cosmetic damage to his GP21.
The crash is currently being investigated by the stewards.
Bastianini – who hurt his leg in the incident – says Zarco’s braking was “very strange” and made it “impossible” to avoid him.
“It’s a really difficult day for me but I think also for all the riders, because after the notice of Jason [Dupasquier’s death], I think we aren’t concentrated for the race,” Bastianini said.
“After, when we are in the grid Zarco braked very strange, very hard and it was impossible to not hit him.
“For me it’s crazy, it’s the only thing I can say.
“I don’t know, my body is so and so and it’s important to recover for Barcelona and we will see what happens in Montmelo.”
Zarco admits he thought his bike would be “ruined” for the race following the collision, but is glad Bastianini wasn’t seriously injured.
“A lot of things happened,” Zarco told Canal +. “Even before the start, Bastianini hit me.
:We’re all coming out of that last corner, accelerating, braking to keep the tyres warm and to be ready for the start.
“And… you can see the picture now [he’s looking at a TV screen]… wow… well, the important thing is that he didn’t get hurt.
“But I thought that my bike, as he hit me, was going to be ruined for the race.
“I looked at my saddle, I saw that it was OK, I took the start. The start wasn’t great, but I was able to hold my position.”
Zarco ran in the podium battle for most of the 23-lap race, but ultimately missed out on a fourth rostrum of the season to Suzuki’s Joan Mir and KTM’s Miguel Oliveira in fourth.