The stewards who made the decision in Melbourne held a virtual meeting on Tuesday to consider a petition for review of the five-second penalty that dropped Sainz from fourth to 12th.
Ferrari needed to present a "significant and relevant new element" but, after considering telemetry data and witness statements, the stewards decided they had failed to do so.
"There is no significant and relevant new element which was unavailable to the parties seeking the review at the time of the decision concerned. The petition is therefore dismissed," they said.
Sainz was deemed "wholly to blame" for the first corner collision with Aston Martin's Fernando Alonso, who ended up third, at the final re-start of the triple red-flagged race.
The Ferrari driver, who was punished during the race without a hearing, said at the time it was the "most unfair penalty I've seen in my life".
"Very disappointed that the FIA did not grant us a right to review," Sainz said on Twitter.
"Two weeks later, I still think the penalty is too disproportionate and I believe it should have at least been reviewed on the basis of the evidence and reasoning we have presented.
"We have to continue working together to improve certain things for the future. The consistency and decision-making process has been a hot topic for many seasons now and we need to be clearer for the sake of our sport."
IN-RACE DECISION
The drop meant Ferrari, the sport's oldest and most successful team, drew a blank from the third round of the season after Charles Leclerc retired on the opening lap.
Ferrari had argued that the stewards had treated other incidents differently and referred to a 2014 Canadian Grand Prix case involving Mexican Sergio Perez, then driving for Force India, as a precedent.
The stewards, who heard from Ferrari boss Fred Vasseur, Sainz and racing director Laurent Mekies, said the decision was made in-race because they deemed it to be clear who was at fault.
They found the telemetry data presented to be "at best ambiguous" and felt it in fact corroborated the decision to find Sainz wholly to blame.
The Spaniard had said he had to brake harder because his car's tyres were cold, with a slow formation lap contributing to that problem, and he also had the sun in his eyes.
The stewards said all drivers had to adapt to the track and tyre conditions.
"Logic would dictate that the position of the sun would have equally impacted other drivers too. It is not a justifiable reason to avoid a penalty for a collision," they said.
Ferrari said they were disappointed by the outcome and felt they had provided sufficient significant new elements "especially in the context of the particular conditions and multiple incidents that occurred during the final restart.
"We are now looking forward to entering broader discussions with the FIA, F1 and all the teams with the aim of further improving the policing of our sport..."
