"If Only" was inscribed on the image of Trump lying with his eyes closed adjacent to a gravestone, surrounded by daisies, with the inscription "Donald J. Trump 1946-2024".
The image was posted on Hamill's verified Bluesky account.
Hamill, who played Luke Skywalker in the classic Star Wars films that debuted in 1977, wrote that Trump "should live long enough to witness his inevitable devastating loss in the midterms, be held accountable for his unprecedented corruption, impeached, convicted & humiliated for his countless crimes Long enough to realise he'll be disgraced in the history books, forevermore."
The White House responded on X, calling Hamill "one sick individual".
"These Radical Left lunatics just can't help themselves," a post from the White House press team said.
"This kind of rhetoric is exactly what has inspired three assassination attempts in two years against our president."
Hamill later removed the gravestone image and sought to clarify his remarks.
"Actually, I was wishing him the opposite of dead, but apologise if you found the image inappropriate," he wrote on Bluesky.
In April, a man stormed a security checkpoint and fired a shotgun outside the White House Correspondents' Association dinner in what authorities said was an attempt to assassinate Trump.
Trump was shot in the ear in 2024 at a rally in Pennsylvania. The shooter was killed by the Secret Service. Also in 2024, a man was found hiding in bushes with weapons close to where Trump was golfing. He was convicted of attempted assassination in February.
