The Spaniard was handed a post-race 10-seconds penalty for an infringement during his pit-stop when he was serving a five-second penalty for making an incorrect start.
Beaming with satisfaction with his stirring drive for Aston Martin, Alonso said he was not seriously upset by the decision and felt encouraged by the performance of his car and the team.
"I'm not too upset," he said. "It was good and it doesn't hurt much. I was on the podium, I took the pictures, I got the trophy. I celebrated with the champagne. Now I have three points less I don't have 15, I have 12.
"I think it's more of an FIA poor show today more than disappointment for ourselves.
"You can't apply the penalty 35 laps after the pit-stop. They had enough time to inform us. If I knew about the penalty, I would have had 11 seconds with the car
"I think we were faster here than in Bahrain and it looks very good for the future."
The 41-year-old two-time champion had taken the lead at the first corner of the 50-lap race, but he was given a five-second penalty for starting from an incorrect position, too far to the left in his grid slot.
He attempted to serve the penalty when he came in for his pit-stop, after being passed by Red Bull's race winner Sergio Perez, but a mechanic, his rear jackman, was adjudged to have touched the car before the five seconds had elapsed.
It was a similar infringement to that of Alpine driver Esteban Ocon who was given three penalties at the season-opening Bahrain Grand Prix.
The decision was not made public until the end of the race -– and after the popular Spaniard had appeared on the podium and in the post-race interviews.
Alonso, making his record-increasing 357th race start, heaped praise on his team after the race.
"These guys have made a fantastic car, a fantastic execution of the race here and in Bahrain, with the strategy and now two podiums.
"These guys give me power and I push all the way through and in qualifying laps too. The Red Bulls are out of reach, but the rest were behind us so I'm happy with that."
Aston Martin team chief Mike Krack said they were studying the videos before deciding if they would appeal.
"We are studying this now and we don't know yet how we are going to handle it."
