The Tesla founder made reference to United in a late-night tweet.
Musk wrote: “To be clear, I support the left half of the Republican Party and the right half of the Democratic Party!
“Also, I’m buying Manchester United ur (sic) welcome.”
His post quickly garnered a lot of attention, receiving more than 36,000 retweets and almost 200,000 likes within a couple of hours.
But, responding to Tesla owners asking if he was serious, Musk tweeted in reply: “No, this is a long-running joke on Twitter. I’m not buying any sports teams.”
United have been owned by the Florida-based Glazer family since 2005.
Their ownership has regularly come under fire from fans due to the debt, dividends and mismanagement that followed their controversial takeover.
The Glazers have also overseen a sharp decline in performances and results in recent years.
The record 20-time champions of England have not won a Premier League title since Sir Alex Ferguson’s final season in charge in 2012-13 and no kind of silverware for five years.