The Alpine driver picked up three five-second penalties for track limits offences over the course of the race.
He took the first at a pit stop, while the others were added to his race time, leaving him in 12th place behind the also penalised Sergio Perez and Lance Stroll.
“It wasn't a good day,” said the Frenchman when asked by Autosport about his difficult race. “I made too many mistakes with the track limits, and it cost me 15 seconds.
“So I can only be disappointed with myself because obviously, you're talking a few centimetres, which is nothing, but I paid a big price for it and missed out on the points. So I've just got to learn from this.
“All in all it was a tough day. I had a good start but went on the outside and had to slow down with the Mercedes [incident] in front of me, so lost another two positions.
“And then after that the whole race we had energy management issues, which cost me straight-line speed throughout the whole race. I was just trying to compensate for it, and took too many risks. So just not a good day from us."
Gasly admitted that one of the problems was that track limits warnings came too late from the FIA, via his engineer.
"It was the story of the whole race,” he said. “I don't have any excuses because it's the same for everyone, and at the end of the day, I took too many obviously.
“I don't know how many track limits there have been the whole race, but we were always two steps behind from what's happening, and I think it wasn't an easy day for us."
Like other drivers Gasly found the race hard physically: "It was the toughest race of the year. It was clearly very hot in the car, and very physically challenging. I knew it would be like that.
“And I know I'm training really hard, and I have one of the best physical conditions in the paddock. So I usually embrace these conditions.
“And I know it's challenging for everyone, but today I just didn't do a good enough job, and I need to learn from this track limits story."
Meanwhile, Gasly’s team-mate Esteban Ocon, who was hit hard by track limits penalties in Austria, says he worked hard to avoid a repeat. The Frenchman eventually finished a solid seventh.
"I had one on lap one of the race,” he said. “I was like, if we start like that, then it's going be a pain! I got a snap mid-corner and I went wide. After that, I think I stayed really clear.
“Like I was not even touching the white line anymore, staying mid-track to make sure something like Austria doesn't happen.
"I had a very, very good first lap. I passed Lando [Norris], I passed Pierre, and I was just making my way through when we were boxing, and stuff like that.
“So I didn't waste any moment in terms of overtaking and all that, so I think it is a pretty well maximised race."
