A protester holding a sign against racism and hatred is removed from Donald Trump's Iowa rally. REUTERS/Scott Morgan Real-estate mogul Donald Trump's Tuesday-night campaign rally was repeatedly disrupted by protesters wielding whistles.

Trump's events are often interrupted by hecklers, but the Republican presidential front-runner usually brushes them off, sometimes by mocking their supposedly weak voices.

However, the whistles appeared to genuinely bother Trump as he spoke Tuesday in Iowa City, Iowa.

"Oh no, not again," Trump said at one point.

"Throw them the hell out of here. Am I allowed to rip that whistle out of the mouth? I'd rip that whistle," he continued, pausing as if he were about to curse. "I'd rip it right out. I would rip that whistle."

He then floated the whistle-taking idea to his audience members: "Should somebody do that?"

The whistles continued.

"Boy, oh boy, oh boy. OK. Maybe we should bring that person up. We'll have a little 'debate' with that person," Trump said as his audience cheered. "Isn't it terrible though? Isn't it terrible? I mean, where do these people come from? You really wonder. Hey security, get them the hell out of here, would you please? ... Get them out of here!"

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