The image shows the president in a boxing ring, without a shirt, wearing a gold belt.
The president's head is superimposed above the shoulders of Rocky Balboa, who was famously portrayed by Sylvester Stallone in the Oscar-winning blockbuster "Rocky."
Trump tweeted the message on Friday, leaving many on social asking: What does this mean?
One person tweeted, "is this real life?"
"Best tweet ever. Liberal heads are exploding everywhere. I love it," tweeted another user.
"Donald please I just got my wife back!," wrote another person.
Other comments include:
"Is this doctored?"
"I'm embarrassed at how hard this stuff makes me laugh."
"This is your best tweet yet."
"Should have put a warning on this #iwasntReady".
President Trump didn't tweet an explanation along with the photo, leaving many to speculate.
"Is this...is this really how you see yourself lmaoooo," read another tweet.