Trump made the remarks in Richmond, Virginia in front of a crowd of 5,000 the day after the Democrats met in Las Vegas for their first debate.
"I watched Hillary last night -- 'we're gonna give this, we're gonna give that,'" he said. "The poor woman, she's gotta give everything away because this maniac that was standing on her right was giving everything away, so she's following! It's what's happening."
Sanders admitted that he is a Democratic Socialist, but Trump pushed the point further during the event.
"I call him a socialist-slash-communist because that's what he is," he said.
"He's gonna tax you people at 90 percent; he's gonna take everything!”
When asked to comment, Sanders campaign spokesperson Michael Briggs told ABC News, "If we weighed in every time Donald Trump said something stupid we wouldn't have time to do anything else."
A small group of protesters made the Donald pause his remarks for a few seconds as they chanted for immigration reform and climate change –- some got into a scuffle with Trump supporters until they were removed from the venue.