President Barack Obama’s speech in Cuba calling for democracy and human rights on the island was relatively good, but don’t fool yourself: It will be drowned in an avalanche of Castro government propaganda in the coming weeks and might soon be a faint memory in most Cubans’ minds.

This is not meant to dismiss Obama’s speech in Havana as a waste of time, nor his opening to Cuba as a mistake, as Obama’s right-wing critics are already saying. In fact, Obama’s decision to reverse U.S. policy about Cuba was a good decision after decades of failed U.S. efforts to isolate the island.

But Obama could have done it much better. The U.S. president was too diplomatic, too conciliatory and too nice to Cuban dictator Raúl Castro.

He could have made the same trip by holding an official meeting in Havana with Castro, but delivering a somewhat stronger — while respectful — speech, without singing praises to Cuba’s alleged achievements in health and education that collapsed decades ago, and without appearing next to Castro enjoying a baseball game.

To his credit, in his speech broadcast live on the island at the end of his historic three-day visit, Obama said that “I believe citizens should be free to speak their mind without fear, to organize and to criticize their government, and to protest peacefully. And that the rule of law should not include arbitrary detentions of people who exercise those rights.”

He added, “And yes, I believe voters should be able to choose their governments in free and democratic elections.”

Furthermore, he stressed over and over that the United States is no longer an enemy of Cuba, debunking the Castro regime’s claim that it needs to suppress fundamental freedoms because the island is threatened by Washington. All of that was well conceived, and well delivered.

But many human rights advocates, including those who support Obama’s Cuba policy, expected a less abstract, more specific speech.

Jose Miguel Vivanco, head of Human Rights Watch’s Americas department and a supporter of Obama’s opening to Cuba, said that “Obama could have done much more to highlight the reforms that are urgently needed to end” Cuba’s police state.

“What Obama did not do was talk about the specific ways in which the Castro government denies these freedoms, such as blocking access to websites of independent journalists, denying rights to labor unions, threatening and detaining people to prevent them from participating in peaceful protests and political meetings, and using an Orwellian law to imprison critics for up to four years for ‘pre-criminal dangerousness,’ ” Vivanco said.

Also to his credit, Obama met with leading Cuban dissidents at a private meeting at the U.S. Embassy after his speech. Among those attending were Berta Soler, a leader of Ladies in White, activist Guillermo Fariñas and Cuban Human Rights and National Reconciliation Commission founder Elizardo Sánchez Santacruz.

Shortly before Obama’s trip to Cuba, Sánchez had cautioned me in an interview not to buy into speculation that a nationally broadcast speech by Obama would have a big impact in Cuba. He reminded me that there are no independent newspapers, nor radio or television stations on the island, and that Internet service is scarce and censored.

Former President Jimmy Carter, Pope John Paul II and several other foreign dignitaries were allowed to make public speeches in Cuba through the years, but their impact was short-lived, he said.

Referring to Obama, Sánchez told me that “Castro may allow him to say whatever he wants because later, with his huge domestic and foreign propaganda machine, and with police intimidation, Castro can erase his message from people’s memory.”

And as for the dissidents’ meeting with Obama, Castro’s propaganda machine will stress that it took place at the U.S. Embassy, citing that as alleged proof of its ridiculous claims that all oppositionists in Cuba are “U.S. mercenaries.”

My opinion: Obama’s conciliatory message will make it increasingly difficult for the Castro dictatorship to continue claiming that it can’t hold free elections or allow political parties because the country is under threat of a U.S. invasion.

But don’t believe the conventional wisdom in the U.S. media that Obama’s calls for human rights and democracy may mark a turning point in Cuba’s history. Only an international diplomatic offensive in support of Cuba’s peaceful opposition will help force a political opening in Cuba. That’s a pending assignment for Obama, or for his successor.

— Andres Oppenheimer is a Latin America correspondent for the Miami Herald.