Sanchez, whose critical "Generacion Y" blog received 1.2 million hits in February, said Cubans can no longer visit her Web page and two other home-grown bloggers on the Web site on a server in Germany.
All they can see is a "error downloading" message.
"So the anonymous censors of our famished cyberspace have tried to shut me in a room, turn off the light and not let my friends in," she wrote in her blog on Monday.
Sanchez said she cannot directly access her Web site from Cuba to update postings anymore, but has found a way to beat her
The 32-year-old philology graduate has attracted a considerable readership by writing about her daily life in Cuba and describing economic hardships and political constraints.
She has criticized Cuba's new leader, Raul Castro, who formally took over from his ailing brother Fidel Castro last month, for his vague promises of change and minimal steps to improve the standard of living of Cubans.
"Who is the last in line for a toaster?" was the title of a recent blog that satirized the lifting of a ban on sales of computers, DVD players, and other appliances Cubans long for, though toasters will not be freely sold until 2010.
In a country where the press is controlled by the state and there is no independent media, Sanchez and other bloggers based in Cuba have found in the Internet an unregulated vehicle of expression.
"This breath of fresh air has disheveled the hair of bureaucrats and censors," she said in a telephone interview, vowing to continue her blog. "Anyone with a bit of computer skills knows how to get around them," she said.
The aim of government censors is to block readership in Cuba, where people have limited access to the Internet, she said.
"They are admitting that no alternative way of thinking can exist in Cuba, but people will continue reading us somehow," she said. "There is no censorship that can stop people who are determined to access the Internet," she said.