The 20-year-old Japanese, who struggled with a back injury in losing 6-4, 6-4 to unseeded Anastasija Sevastova, opened up afterward on dealing with ramped-up expectations, AFP reported.
The world number six made headlines last month when she stunned Serena Williams in New York to win her maiden Grand Slam, in a final overshadowed by the American's bitter row with the chair umpire.
Osaka's shock triumph – at such a young age and against one of the greatest tennis players of all time – propelled her into the limelight.
It is a place that she is not altogether comfortable in.
"I think definitely as the weeks go by, I have this feeling of wanting to prove myself. I think that sort of takes a toll on me a little bit because I stress myself out in a way," said Osaka.
"If you don't win a tournament, then people will say, 'Oh, she hasn't won a tournament.'
"If you haven't won a Slam, they'll say, 'She hasn't won a slam.'
"Then if you win one Grand Slam, they're like, 'Oh, she only won one Grand Slam.'
"I know it's bad, but I sort of read the comments (online or in media). I'm just, like, 'Oh, I guess I have to do more, to be better.'"
Osaka, who was attempting to reach a third straight final after New York and Tokyo's Pan Pacific Open, was unhappy with her behavior in Friday's quarterfinal victory over Zhang Shuai.
Osaka had been close to tears during the second set and threw her racquet, before recovering her poise.
She was more composed against the Latvian Sevastova, even though she was hindered by her back, which she said was more a case of fatigue than anything more serious.
Asked by AFP at her post-match press conference why she appeared happier in defeat than she did after winning on Friday, Osaka said, "I don't have any regrets from today.
"But my back's sort of been bothering me since the beginning of the tournament.
"I'm kind of happy that I was able to get this far."