The United States embassy in Tajikistan said on Thursday it had received information about possible attacks on large public gatherings in the Central Asian nation and its border crossings with Afghanistan.
The embassy said in a statement that "terrorist groups" may carry out such attacks, but did not name them.
It urged U.S. citizens to avoid large crowds and public transportation.
Tajikistan often reports clashes with Afghan drug smugglers along the border.
The former Soviet republic is also planning a series of events in parks and other public places to mark a new holiday, President's Day, on Nov. 16.
President Imomali Rakhmon, in power since 1992, faced a coup attempt by a senior defence official in September 2015.
His government has since banned an Islamist party, once the country's main opposition.