The first thing that Raúl Castro had to prove to the Cuban people was that the restoration of diplomatic relations with the United States would not lead to even a nominal improvement in the human or civil rights of his slaves, and he is proving it by cracking down on Cuba's leading dissidents even more arbitrarily and ruthlessly than usual.
It is likewise a warning to Obama not to demand more than he got, which was nothing. No prior-conditions means no prior-conditions and no concessions means no concessions. This is the deal that Obama struck with Castro, and Castro expects and demands that the neophyte president uphold it to the letter, which, given Obama's silence, is precisely what he intends to do. Obama in fact is so strict in his interpretation of the terms of his capitulation to Castro that he does not even dare to say one word on behalf of those being trammeled in Cuba because he decided that Cuba's dissidents were expendable, just as JFK decided at the Bay of Pigs that the freedom fighters were expendable, and again as he decided in the Kennedy-Khrushchev Pact that all Cubans were expendable.
Although there was no clause in the Obama-Castro Pact that addressed human rights by name or implication, its supporters assumed that the mere existence of any agreement, especially one wholly beneficial to the regime, would guarantee at least a certain discretion on its part when it came to upping the level of repression. But, on the contrary, the agreement provided Castro with an excuse to accelerate it, not that he ever needed one. Note also the utter contempt which Castro has shown for his camp followers abroad: as if it were not hard to defend the indefensible without also having to respond to every new usurpation in real time, They don't have the luxury any more of claiming that there is more in this agreement than meets the eye, and that, by-the-by, there will be pie in the sky for all Cubans.