Sabalenka, who appeared to sarcastically bow to the crowd following the win, said she initially thought the boos were aimed at her.
"It was a very tough match, I mean tough emotionally.
I'm sorry guys, I didn't get it at first, I thought this booing was against me so I was a little surprised," she said.
The Belarusian raised her level again late in the match to save two breakpoints and close out the victory in 71 minutes.
Reporting by Shrivathsa Sridhar in Paris, editing by Ed Osmond and Hugh LawsonOur Standards: The Thomson Reuters Trust Principles.