The president lamented that his military âcanât act like they would normally actâ by being heavy-handed with refugee families.
He blamed âhorrible laws that Democrats will not changeâ and said he was considering deploying more troops to the Mexico border to stop migrants attempting to cross into the US.
Speaking to reporters in Texas, Mr Trump said: âIâm going to have to call up more military.
"But our military, donât forget, canât act like a military would act because if they get a little rough, everybody would go crazy. So our military canât act like they would normally act, or letâs say another military from another country would act.
âWe have all these horrible laws that the Democrats will not change, they wonât change them. And I think they are going pay a very big price in 2020 for all of the things. I think the border is going to be an incredible issue.â
Mr Trump went on to depict migrants â many of whom have fled poverty, violence or persecution in Latin America â as criminals who would murder Americans and steal their homes.
He said: âThink of these people â supposing I said, letâs have an open border â they will flood your houses, they will shoot you, theyâll take over your house, theyâll take your car and theyâll probably stay there.â
Mr Trump plans to aggressively push for tougher screening that will make it far more difficult for migrants fleeing persecution in their home countries to secure asylum in the US, a senior administration official said this week.
The president is reportedly also considering resuming the controversial policy of separating migrant children from their parents at the border.
He has purged senior immigration officials in the Department of Homeland Security as he seeks to take it in a "tougher direction".