They said it did not amount to a "covert" operation, although they said the government takes steps to maintain discretion when working in "non-permissive environments" such as Cuba.
Documents obtained by the AP showed that the network, dubbed ZunZuneo after the Cuban word for hummingbird, operated from 2009 until it vanished in 2012.
Some 40,000 island cellphone users signed up and used ZunZuneo to receive and send text messages, mostly innocuous jokes or snippets of international, sports and entertainment news.
However the AP revealed that the network, built using secret shell companies and financed through a foreign bank, sought to first build an audience of mostly young people and then nudge them toward dissent.
"ZunZuneo joins an extensive list of secret anti-Cuban operations" including the failed Bay of Pigs invasion of 1961 and plots to assassinate Fidel Castro, Prensa Latina said.
In a statement late Thursday, Josefina Vidal, director of U.S. affairs at Cuba's Foreign Ministry, demanded that Washington halt "its illegal and clandestine actions against Cuba." She said the ZunZuneo case "shows once again that the United States government has not renounced its plans of subversion against Cuba."
Cuba has one of the lowest Internet penetration rates in the world, though the country has taken small steps to expand access. Last year it opened about 200 cyber-cafes around the country, though at $4.50 an hour, many Cubans are effectively priced out. The government also controls nearly all traditional media.
If Internet access remains rare and precious, cellphone use is increasingly common among the island's population of 11 million. Official statistics say there were about 1.8 million active Cuban mobile accounts in 2012, compared with 400,000 in 2007.
On the streets of Havana, some echoed their government's complaints about U.S. interference and ZunZuneo.
"Coming from them (the United States), nothing can surprise us anymore," said 25-year-old Claudia Garcia.
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Peter Orsi on Twitter: www.twitter.com/Peter_Orsi