As the top U.S. diplomat for Africa visits Cameroon, pro-government groups are protesting what they call Tibor Nagy's interference in Cameroon's internal affairs.
U.S. Assistant Secretary of State for African Affairs Nagy and the European Union representative Federica Mogherini recently called on Cameroon to free opposition leader Maurice Kamto and 150 of his supporters.
They also urged Cameroon authorities to work harder to stop the violence in its western, anglophone separatist regions.
The coordinator for Monday's protest, Lilian Koulou Engoulou, said the demonstrators want Nagy to hear them and take their message back to Washington.
America should stop interfering in Cameroon's internal issues, Engoulou said, and should help end the crisis in the English-speaking northwest and southwest regions by stopping Cameroonians based in the U.S. from funding what he calls terrorists and destabilizing Cameroon.
The last comment refers to separatist leaders based in the U.S. who have appealed on social media for contributions to help the fighters back home.
Communications Minister Rene Emmanuel Sadi, who has previously accused the U.S. of harboring separatist leaders, said last week that Cameroon was outraged by Nagy's statements.
Aime Manga of Cameroon Rights Watch, a local group, said officials should take Nagy's comments as helpful suggestions rather than criticism.
It is public knowledge that Cameroon has a serious political and social crisis, he said, and Nagy's comments bring hope to many who want democracy.
Cameroon has detained Kamto and his supporters since January for taking part in anti-government demonstrations. They are being tried in military courts for charges that include rebellion and could face the death penalty.
In comments made days before his arrival Sunday in Yaounde, Nagy said it's not always positive to arrest opposition members during times of crisis.
He also called the death and suffering in Cameroon's rebellion heartbreaking and urged authorities to do more to end the fighting.