Hundreds of Cuban government supporters have heckled members of the "Ladies in White" rights group marching in protest through the streets of Havana.
The women - wives and mothers of jailed dissidents - are staging a week of protests on the anniversary of Fidel Castro's 2003 Black Spring crackdown.
They are demanding the release of some 50 government critics still being held.
On Wednesday, police briefly arrested some of the women, known as the "Damas de Blanco" because they dress in white.
Those marching on Thursday, the fourth day of protests, included the mother of Orlando Zapata, who died last month after an 85-day prison hunger strike.
"We repudiate them because they are against the revolution and we will defend this revolution until the end," said Yamile Gonzalez, one of the pro-government supporters.
A US state department spokesman said Washington was "dismayed that a peaceful march was disrupted by the Cuban government".
Amnesty International has urged Havana to ensure the safety of the women, saying some were beaten by police following Wednesday's arrests.
Cuba has lashed out at the criticism, saying the dissidents are common criminals who are paid by the US to destabilise the government.
