The Mobil 1 HSV Racing driver made contact with the rear of de Silvestro's #78 Nissan at the penultimate corner of the Adelaide Parklands circuit, which resulted in a spin for the Swiss rookie.
De Silvestro had been attempting to file into pit lane when the contact occurred.
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Stewards reviewed the matter after the race before deciding the incident warranted no further action, according to Supercars.
De Silvestro came home a lap down in 23rd position but felt the clash ruined her race.
“I was trying to get in the pits and he didn't want to let me get in the pits I guess,” de Silvestro told Speedcafe.com.
“I tried to go as fast as I could around that corner and then he just hit me and took me out.
“It was really frustrating because it ruined our race for sure, and I think that's not the way to really go about it.”
Courtney said he didn't realise de Silvestro was trying to enter pit lane shortly before the contact happened.
“I was trying to pass Simona and she didn't have her blinker on,” Courtney told the official Supercars website.
“I didn't know she was coming into the pits and I was up the inside.
“That's racing. I'm sorry, I didn't mean to hit her, but we're all racing hard.”
Courtney managed to power on to fourth at the chequered flag.