A group of Cuban dissidents has sharply criticised the US for measures aimed at speeding up the end of Fidel Castro's communist rule.
Oswaldo Paya is trying to effect change from within Cuba
Leading dissident Oswaldo Paya said it was up to Cubans, not the US, to bring about change in the country.
US President George W Bush on Thursday endorsed new sanctions and a $36m plan to promote change in Cuba.
Two other Cuban dissidents handed in a protest letter at the US diplomatic mission in Havana.
One of the authors, Manuel Cuesta, said the US had "no right to set the pace of a transition in Cuba".
The other, fellow dissident Eloy Gutierrez Menoyo, said:
"This is a total interference that does not benefit the building of democracy in Cuba."
He said his letter to US Secretary of State Colin Powell said the US plan was tantamount to incitement to armed conflict.
"It is not appropriate or acceptable for any forces outside Cuba to try to design the Cuban transition process," said Mr Paya, winner of the European Parliament's Andrei Sakharov human rights prize, in a separate statement.
He has led the Varela Project, collecting 25,000 signatures seeking to effect political and economic reforms from within the current system.
Veteran Cuban human rights activist Elizardo Sanchez described the proposals as "totally counterproductive and clearly involve meddling" from abroad.
Bush would like to see Castro out of power
Mr Bush agreed to tough new measures suggested in a report by the Commission for Assistance to a Free Cuba.
The proposals are designed to hasten the fall of Cuban leader Fidel Castro, and prevent his younger brother Raul Castro succeeding him.
Measures included renewed efforts to broadcast pro-democracy messages in Cuba and further curbs on money sent home by Cuban exiles.
"We're not waiting for the day of Cuban freedom, we are working for the day of freedom," Mr Bush said.
Cuban-American Republican members of Congress reportedly welcomed the measures.
Democrat presidential candidate John Kerry said Mr Bush was playing election-year politics.