"People say 'Donald Trump has really leveraged social media.' No, he hasn't — he's horrible on Twitter," Cuban said of the presumptive Republican presidential nominee. "He doesn't understand Twitter whatsoever, and if he was really into social media, he'd be using every other social media source as well."
While Trump makes the occasional appearance on Facebook, Cuban called the thought of seeing Trump on Instagram or Snapchat "hysterical."
"The people who follow Trump, they're not looking for substance, and he's smart not to provide some," Cuban said.
Cuban accused the business mogul of hurling harmless insults like "nerf balls" against technology CEOs like Jeff Bezos and Mark Zuckerberg to stir up support. Cuban, a dot-com founder and "Shark Tank" investor, called Trump's campaign a "campaign about nothing."
"I love to mess with Donald on Twitter because he doesn't get it. He doesn't understand the way Twitter works," Cuban said.
A Trump campaign spokeswoman did not immediately respond to a request for comment.
Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."