The Finn was less than two tenths behind team-mate Lewis Hamilton, as the pair locked out the front row for the Silver Arrows.
However, Bottas believes he had more time in him, and that his British team-mate just got more of a complete lap in.
“First of all, Lewis had quite a last lap, so congratulations for that,” Bottas said.
“In my first lap I felt there was plenty I could improve and the gap would get smaller between us than in the first runs.
“In the second run I think there was definitively some track improvement, and both of us managed to find some time.
“But he just managed to get a little bit of a more complete lap, in the end.”
The Finn, who is still yet to win a grand prix this season, also struggled to get clean run during the qualifying session.
“I think that what hurt me a bit was there was a couple of runs in qualifying where I couldn’t get a good lap in,” he admitted.
“I think with the Ultrasoft tyres, at the start of Q2 and in some other runs I really struggled with some things in the car.
“I think I lost a lot a little bit of time in Turns 17 and 18, it’s very difficult to get it perfectly right.
“He’s performing well, he was tough to beat this time, there was probably a little bit more time in me, but he also did a really good lap.”