The US Secret Service says it is “aware” of a social media post by Elon Musk in which he said that “no one is even trying” to assassinate President Joe Biden or Vice-President Kamala Harris.
Mr Musk has since deleted the post and said it was intended as a joke.
His post on X, formerly Twitter, came just hours after the suspected attempted assassination of Donald Trump at his golf course in Florida on Sunday.
The tech billionaire is a close ally of Trump, who has vowed to enlist Mr Musk to run a “government efficiency commission” if he wins a second term as US president.
Many X users criticised Mr Musk’s comments – which were accompanied by a raised eyebrow emoji – with some alleging that the post was a form of incitement against the US president and vice-president.
In a statement, the White House condemned the post, saying that “this rhetoric is irresponsible”.
“Violence should only be condemned, never encouraged or joked about,” the statement said, adding that there should be “no place for political violence or for any violence ever in our country”.
When contacted by the BBC, the US Secret Service said only that it is “aware” of the post.
“As a matter of practice we do not comment on matters involving protective intelligence,” the statement added. “We can say, however, that the Secret Service investigates all threats related to our protectees.”
After deleting the post, Mr Musk tweeted that “one lesson I’ve learned is that just because I say something to a group and they laugh doesn’t mean it’s going to be all that hilarious as a post on X.”
“Turns out that jokes are way less funny if people don’t know the context and the delivery is in plain text,” a subsequent post read.
The controversial tech mogul is considered a close ally of Trump and formally endorsed him in the aftermath of a separate assassination attempt against the former president that took place at a rally on 13 July in Butler, Pennsylvania.
In that attempt, the suspect fired multiple rounds, injuring Trump and killing an attendee at the rally.
Since then, Mr Musk has often tweeted or re-posted messages critical of both Biden and Harris and in support of Trump.