"He’s elected eight anarchist DAs in the United States. He’s a horrible human being.”
Statements about the supposed reach of the power of Mr Soros, who was born in Hungary and survived the Holocaust, have become a mainstay of antisemitic conspiracy theories.
Last year, Mr Trump said "a lot of people say" that Mr Soros was funding the so-called migrant caravan.
Jonathan Greenblatt, chief executive of Anti-Defamation League, tweeted: "Opposing Soros isn't what's antisemitic.
"Saying that he controls ambassadors, employs FBI agents and isn't 'Jewish enough' to be demonized is."