Demonstrators threw stones and burned makeshift barricades on Wednesday, the latest in a string of protests since a 2021 coup by the military, which has dragged its feet on promises to hand back power to civilians.
The two doctors, who asked not to be named, said they received two people who had died during the clashes. A police spokesperson did not confirm the deaths but said that about 20 police were injured.
A committee of opposition groups, civil society organizations and activists had called for peaceful demonstrations on Wednesday and Thursday in Conakry and elsewhere.
"Let no one shrink from intimidation and repression," they said in a joint statement on Tuesday. "We will liberate our country and prevent any attempt to confiscate our democracy and fundamental freedoms."
Last October, Guinea's military government proposed a two-year transition to elections, down from a three-year timeline earlier rejected by the regional political and economic bloc, the Economic Community of West African States.
Many remain unappeased. Black smoke from burning tires filled the air in one Conakry neighborhood on Wednesday as protesters faced off against police in riot gear and armored cars.
Elsewhere, protesters threw stones at police as white clouds of tear gas drifted across the street.
Small-scale demonstrations also took place in Nzerekore, a town in the south-east, and in the central town of Dabola, local residents told Reuters by phone.
"If it continues like this, it won't be good. I don't like demonstrations. We like peace. These demonstrations are really tiring," said Conakry resident Alassane Diallo.
Previous protests have proved deadly. Organizers reported the deaths of several protesters from gunshot wounds earlier this year and in 2022.