Cuba has released about 70 members of the Damas de Blanco (Women in White) opposition group who were detained on March 18.
However, authorities warned the group not to attend any events related to the March 26-28 visit to Cuba of Pope Benedict XVI.
Damas de Blanco leader Berta Soler was among those released.
She told Reuters that officials had told her not to attend the pope's Masses, but that she planned to do so anyway.
The group has also requested a meeting with the pontiff to discuss human rights in Cuba.
Earlier on March 19, U.S. National Security Council spokesman Tommy Vietor called on Cuban authorities to "abandon their tactics of intimidation and harassment" regarding opposition groups.
With Reuters, dpa, and AFP reports