The US has suspended more than $47 million in military aid to 35 countries that have not signed deals giving US citizens immunity from the International Criminal Court (ICC) tribunal.
Agence France Presse reported that sanctions were placed on the nations after they failed or refused to sign Article 98 agreements before the 1 July deadline set by the US government.
South Africa, Malawi, Samoa and Zambia are among the nations affected by the US action.
The ICC has been set up to try cases of war crimes, crimes against humanity and genocide. The Article 98 agreement protects American service members from "arbitrary" or "political" prosecution by the ICC, a US State Department spokesperson said.
The cut in aid is not a large amount in proportion to the total $4 billion a year the US gives in foreign military assistance. But the move is expected to send a political message.
Human Rights Watch has accused the US of using bullying tactics on "small, vulnerable, and often fragile democratic governments".