Serena Williams is putting a Paris hotel on blast ... calling out the establishment for denying her family access to a rooftop restaurant -- despite it being completely "empty."
The 42-year-old tennis legend went to X to publicly send a message to The Peninsula Hotel on Monday ... sharing her frustrations with how her visit went down.
"Yikes," Williams stated. "@peninsulaparis I’ve been denied access to rooftop to eat in a empty restaurant of nicer places but never with my kids. Always a first."
Williams also made sure to include a sign on the building ... just to make sure there was no confusion over the place in question.
Fans of Williams ripped the hotel in the comments for rejecting the 23-time Grand Slam winner ... including one who said, "Who doesn't make room for a queen?"
Williams has been enjoying all the competition at the Paris Games ... and was part of the Olympic torch-lighting handoff with Rafael Nadal, Carl Lewis, and Nadia Comaneci.
Williams -- who retired from tennis in 2022 -- was also spotted at the Novak Djokovic and Carlos Alcaraz match on Sunday inside the Court Philippe-Chatrier.
We reached out to The Peninsula Paris for comment ... but so far, no word back.