Security chief Oleksander Yakimenko accused protesters of looting weapons and ammunition from government offices and announced a nationwide "anti-terrorist operation."
According to senior U.S. administration officials, such language by Ukraine signals a hardening government position against the protesters.
In a later conference call with reporters, the senior State Department official -- who spoke on condition of not being identified -- expressed concern over the replacement of Ukraine's military armed forces chief. No reason was given for the dismissal of Col. Gen. Volodymyr Zamana.
Russia, which has major historical and economic ties to the former Soviet territory, accuses the United States of playing a role in the widespread protests. The senior State Department official denied that on Wednesday, saying "we completely reject their notion that we have been interfering."
The visa bans announced Wednesday followed an earlier move in January when existing visas of some Ukrainians were revoked over previous unrest, the State Department official said.
This time, the 20 Ukrainians -- none of them from the military -- now banned from getting new U.S. visas "represent the full chain of command that we consider responsible for ordering security forces to move against" protesters on Tuesday, the official added.
Other sanctions in coordination with the European Union also could occur, according to the official, who declined to provide further details.
France also has threatened sanctions against Ukraine over the government's crackdown, with President Francois Hollande calling the protest violence "unspeakable, unacceptable, intolerable acts."
The Obama administration has come under increasing criticism for its foreign policy as talks have faltered on halting Syria's civil war, which left nearly 5,000 people dead in the last three weeks in a particularly violent stretch of the almost three-year conflict.
On Sunday, veteran GOP Sen. John McCain of Arizona called the U.S. policy in Syria an "abysmal failure and a disgraceful one."