Trump added: "You better be smart. They’re taking your jobs. You better be careful."
Trump also appeared to tie his feelings on immigration to his foreign policy approach, saying the United States should withdraw from places like Afghanistan and spend money building American schools instead.
"They don't want us there, and I don't want them," he said.
Trump also mentioned Sen. Marco Rubio (R-Fla.), who spearheaded comprehensive reform in the Senate, in the context of those who want to "let everybody in." Rubio has hurt his standing somewhat with conservatives by pursuing the plan, which included a new path to citizenship for illegal immigrants already in the United States.
Trump, who has flirted with running for president and governor of New York, also took time to target President Obama.
The wealthy entrepreneur noted Obama's disapproval rating in a recent poll was at 54 percent.
"We're getting into Jimmy Carter territory. I never thought I'd see that again," Trump said, apparently forgetting that George W. Bush's disapproval rating peaked well higher than that toward the end of his presidency.
Trump also referred to Carter as the "late, great Jimmy Carter," even though the former president is still alive.