Trump's tweet confirmed an ABC News report that the FBI is reviewing the circumstances surrounding the dismissal of criminal charges against Smollett.
Prosecutors cleared Smollett of all charges earlier this week despite acknowledging that the actor fabricated a street attack on himself in an attempt to get a pay raise. Officials said they dropped the charges in order to focus resources on violent crime.
“We believe he did what he was charged with doing,” Cook County first assistant state attorney Joe Magats said in an interview with Chicago ABC station WLS. “This was not an exoneration. To say that he was exonerated by us or anyone is not true."
Smollett will perform community service and forfeit the remainder of his $10,000 bond to Cook County.
In his tweet Thursday morning, Trump called the case "outrageous" and "an embarrassment" to the country.
A probe led by the FBI and the U.S. Postal Inspection Service is also already underway, confirmed by ABC News in late February, and is focused on whether Smollett played a role in sending a threatening letter to himself prior to the allegedly staged attack on him, according to a law enforcement official briefed on the matter. The probe was not impacted by prosecutors' decision to drop the charges, the official said earlier this week.
ABC News' Stephanie Wash contributed to this report.