Feltman, undersecretary-general for political affairs, met in Cameroon with CAR Prime Minister Nicolas Tiangaye. There, he expressed his commitment to a security deal signed in March between the rebel Seleka coalition and the CAR government.
That deal, dubbed the Libreville Accords, calls for elections within three years and the continued tenure for Tiangaye.
Ousted CAR President Francois Bozize fled to Cameroon after rebel forces seized the capital. Rights officials have expressed concern about security in CAR in the wake of the rebel takeover.
The United Nations estimates that at least 37,000 people have fled CAR because of the violence since January. More than 4 million people, mostly children, have been directly affected by conflict.
Feltman expressed deep alarm at lingering reports of human rights violations in CAR.
U.N. Secretary-General Ban Ki-moon last week welcomed initiatives proposed by African leaders to take measures to stem violence.