The top U.S. diplomat said "As I told President Kagame, we believe people in every country should be able to express their views without fear of intimidation, imprisonment, violence or any other forms of repression."
Secretary Blinken said he also raised the case of "Hotel Rwanda" hero Paul Rusesabagina, a fierce Kagame critic who was sentenced to a 25-year prison term last year on terrorism charges.
In May, the US State Department said Rusesabagina had been "wrongfully detained" by Kigali.
Rusesabagina, then a Kigali hotel manager, is credited with saving hundreds of lives during the 1994 genocide in Rwanda and his actions inspired the Hollywood film "Hotel Rwanda."
He has been behind bars since his arrest in August 2020 when a plane he believed was bound for Burundi landed instead in Kigali. His family has voiced concerns about deteriorating health.
Blinken said he "underscored our concerns about the lack of fair trial guarantees provided to (Rusesabagina)" during his talks with Kagame.