The State Department recommended that U.S. citizens already in Burundi depart as soon as possible. It also mandated the departure of dependents of all U.S. government personnel and nonemergency government personnel from Burundi starting Sunday.
Four police officers and four soldiers were among the dead in Burundi, while nine soldiers and 11 policemen were wounded, spokesman Gaspard Baratuza said.
At least 45 people were arrested following the clashes.
"The United States is deeply alarmed by the attacks that occurred overnight and continue in Bujumbura. We condemn this violence in the strongest possible terms, and we call on all sides to refrain immediately from violence," the State Department said in a statement
France also condemned the attacks and called on all parties in Burundi to choose dialogue and not violence to find a way to end the crisis, the French Foreign Ministry said.
Burundi has seen months of chaos as violence erupted after President Pierre Nkurunziza announced a controversial run for a third term. The subsequent unrest has left scores dead and caused more than 170,000 people to flee the country.
In May, Nkurunziza held onto his office after a failed coup attempt by an army general while the President was in Tanzania.
Tensions in the small East African nation, roughly the size of Belgium, have mounted in recent months. The international community, United Nations and several high-profile nongovernmental organizations have expressed fear that the country could degenerate into an ethnic conflict between Hutus and Tutsis.
During Burundi's 12-year civil war, which ended in 2005, a Hutu majority fought as rebels against the Tutsi-led army. Around 300,000 people were killed.