Garcetti's comments all but confirmed the French capital as the successors to Tokyo in 2020, with LA waiting a further four years for their turn.
The International Olympic Committee (IOC) agreed this month to award the 2024 and the 2028 Games at the same time at a vote in Lima in September, effectively ensuring that the two candidates each will host a Games.
Garcetti told BuzzFeed on Wednesday: "Even though the Olympics will be smart to pick us for 2024, because LA has almost rebooted the brand, 2024 is not probably most likely to happen".
LA is planning to announce their final intentions next week, Garcetti told the US-based online news site.
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"If we are going to go for 2028 or 2024, Paris will get the other," he declared.
"The bid is all but done, we have won."
The double award at the IOC session in Peru is conditional on a prior agreement between the two cities and the IOC. If no agreement is reached, then the session will vote on 2024 only.
Throughout the bidding process Paris has insisted that it is a candidate to host the 2024 Olympics only, while Los Angeles has indicated that it could be open to hosting the Games in 2028.