Trump discussed his plans during an interview with the CBS program "60 Minutes" that will air on Sunday night, Efe news reported.
"What we are going to do is get the people that are criminal and have criminal records, gang members, drug dealers, where a lot of these people, probably two million, it could be even three million, we are getting them out of our country or we are going to incarcerate," Trump said.
"But we're getting them out of our country, they're here illegally," he said.
Trump's statements were more measured than during the campaign, when he took a hard-line position on illegal immigration and promised to carry out mass deportations of the estimated 11 million undocumented immigrants in the US.
The 70-year-old president-elect said he planned to first secure the border and would then decide what to do with the rest of the country's undocumented immigrants.
"After the border is secure and after everything gets normalized, we're going to make a determination on the people that they're talking about who are terrific people, they're terrific people but we are gonna make a determination at that," Trump said.
"But before we make that determination ... it's very important, we are going to secure our border."
Trump said building a wall along the US-Mexican border was still a key part of his security plan but he acknowledged that "some fencing" might have to be used along certain stretches.
"For certain areas I would, but certain areas, a wall is more appropriate," Trump said. "I'm very good at this, it's called construction."