President Trump on Saturday called on Democrats to end a “horrible law” that he says separates children from their parents when they cross the border -- and also accused them of “protecting MS-13 thugs.”

“Put pressure on the Democrats to end the horrible law that separates children from there [sic] parents once they cross the Border into the U.S.” he tweeted.

Trump made the remarks amid a pushback from Democrats and activists at a “zero tolerance” policy enforced by the Justice Department. That policy refers all illegal border crossings for prosecution, including illegal immigrants with children.

Those parents are housed at adult detention centers, and consequently their children are separated from them, registered as “unaccompanied minors” and handed to the Department of Health and Human Services.

Trump has blamed Democrats for the separation of children from their parents before. Last week he told Homeland Secretary Kirstjen Nielsen that the breaking up of families occurred because of “bad laws that the Democrats gave us.”

The Associated Press reported that he appeared to be referring to a 2008 law to combat child trafficking -- a bipartisan law authored by Sen. Dianne Feinstein, D-Calif., but signed into law by Republican President George W. Bush.

While the law says nothing about separating families, it does say that children travelling alone from countries other than Mexico and Canada must be released in the “least restrictive setting” -- namely a family or shelter.

The Justice Department’s zero-tolerance policy, designed to deter prospective illegal immigrants, means that illegal immigrants are no longer released with their children into the U.S. and consequently that their children are separated from them.

“If you cross the border unlawfully, then we will prosecute you. It’s that simple,” Sessions said earlier this month. “If you are smuggling a child, then we will prosecute you. And that child may be separated from you, as required by law.”

SESSIONS SAYS ALL ILLEGAL BORDER CROSSERS WILL BE PROSECUTED; CHILDREN MAY BE SEPARATED FROM PARENTS

But Trump called on Democratic lawmakers to end the practice, apparently as part of a deal that includes the ending of so-called “catch and release” whereby illegal immigrants are released into America while they wait for their court hearing. He also said that the diversity lottery visa and so-called chain migration -- where immigrants can sponsor family members for visas -- must end.

“Catch and Release, Lottery and Chain must also go with it and we MUST continue building the WALL!” he tweeted.

He also returned to accusing Democrats of “protecting” MS-13 gang members. He has said repeatedly that their opposition to strong border policies, as well as the promotion of “sanctuary policies” in states like California and New York, mean criminal gang members get released back into communities.

“Democrats are protecting MS-13 thugs,” he tweeted.

Trump was criticized by Democrats for describing MS-13 members as “animals.” This week he accused Democrats of “trying to defend” them, noting that he was criticized for his remarks by Democratic leaders Rep. Nancy Pelosi, D-Calif., and Sen. Chuck Schumer, D-NY.

Fox News' Samuel Chamberlain and The Associated Press contributed to this report.