The LCR Honda rider was trying to pass Quartararo for 10th on the opening lap of Sunday’s rain-hit grand prix at Rio Hondo when he went into a corner hot and made contact with the Yamaha.
Quartararo was forced onto the painted run-off area, plummeted to 16th in the depleted 17-rider field and was forced into a recovery ride.
The incident was placed under investigation by the FIM stewards, but they deemed no further action was necessary.
Quartararo – who labelled Nakagami a “kamikaze” on French television afterwards – was unhappy with the stewards’ decision.
“No, I don’t understand what they are doing,” Quartararo said on Sunday after the clash.
“I watched the Moto3 race: Ayumu [Sasaki] did an overtake at Turn 5 that was really clean, but he slightly touched [another rider and got a penalty], where in MotoGP we are doing it all the time.
“He [Sasaki] got dropped one position and he [Nakagami] just destroyed my race in one corner and didn’t get anything.”
Nakagami has defended himself, saying he did nothing over the line in the clash – though he concedes he was “overshooting” the corner when he went for the overtake.
“Well, it looks from the outside like it was a little bit aggressive,” said Nakagami, who was 13th in the grand prix.
“But honestly, at that moment I thought I could overtake. But I was slightly overshooting and missing the apex.
“But it wasn’t crazy, it’s not like crazy riding. We touched each other a little bit, but this is racing.
“I have nothing to say. I didn’t make any mistake. Luckily, he didn’t also crash. Of course, he lost the position, I want to apologise. But this is racing.”
This is the second lap-one collision triggered by Nakagami in the space of a year that has gone unpunished, much to his rivals’ annoyance. A first-corner pile-up involving Alex Rins and Francesco Bagnaia in Barcelona last season was deemed a racing incident.
Quartararo was able to recover to seventh after the Nakagami clash.