Piastri was judged to have unnecessarily impeded Kevin Magnussen at the Tamburello chicane during Qualifying 1.
That resulted in a three-place grid drop for the Australian, an especially painful outcome given he’d qualified second fastest.
Once the penalty was announced, team boss Andrea Stella said, “We made our points to be the stewards.
“If this is the assessment and the judgment of the stewards, we respect it.
“We need to improve our operations,” he added.
“We move on and, ultimately, tomorrow we will recover the positions that we lost.”
Speaking ahead of the penalty being confined, Stella admitted the issue stemmed from a breakdown in communication.
“The warning from our race engineer was a little late,” he explained.
“Actually, Oscar checks the mirrors, as we have explained to the stewards.
“He sees that Magnussen is arriving. He assessed the situation: do I go to the left? There’s grass. To the right, there is grass. If I stop at the apex, I’m certainly going to impede. If I cut the chicane, I’m going on the gravel.
“So he realises the best thing to do is just to go through the chicane as fast as possible, which is what he does.
“He actually goes full throttle, he cuts over the kerbs.”
For his part, Piastri acknowledged that he was caught unaware by Magnussen.
“I need to see it back a bit more,” he said when asked about the incident before meeting with the stewards.
“When I looked in the mirrors, I didn’t see any cars coming. Then he was right there.”
Stewards noted Piastri’s response upon realising Magnussen was approaching and the lack of notification over the radio.
However, they still judged it impeding and slapped a three-place penalty on him.
“The Stewards accepted the explanation of Piastri that because of the layout of the circuit at that location, he could not see Magnussen until it was too late, at which time he tried to accelerate away in order to get clear of Magnussen as quickly as possible,” the stewards’ penalty decision outlined.
“Traffic management for slower cars is an extremely important part of the team/driver combination, particularly in Q1.
“In this instance the Stewards determine that the lack of sufficient warning caused an ‘unnecessary impeding’.”
The penalty drops Piastri to fifth on the grid for Sunday’s race, which begins at 15:00 local time (23:00 AEST).