"First off, there is no dream of a dash to another team. I am with my dream team," he said in a comment that has since disappeared.
"Second, there's not a thing in my way as I’m not trying to move. I’m with the people who have cared from day 1. We are the best team! @mercedesamgf1."
Mercedes have won the last six drivers and constructors' titles. One more for Hamilton would equal Michael Schumacher's record seven.
The F1 season has yet to start, however, while Ferrari have said German Vettel is their first choice to partner Moneqasque youngster Charles Leclerc next year.
Vettel, also out of contract at the end of 2020, told reporters last week that he could have a new deal done before the season starts.
Leclerc has a contract to the end of 2024.