By FRANCES ROBLES

President Barack Obama sent a clear message Sunday to Cuban leader Raúl Castro: It's your turn.

If Castro wants to start dialogue with the United States, he should release political prisoners and lower the steep fees the Cuban government charges on money sent from abroad, Obama said.

In the meantime, his administration will examine what other steps can be taken toward ending decades of isolation between Washington and the hemisphere's last communist nation.

''The fact that you had Raúl Castro say he's willing to have his government discuss with ours not just issues of lifting the embargo, but issues of human rights, political prisoners, that's a sign of progress,'' Obama said Sunday at a news conference wrapping up the Fifth Summit of the Americas. "And so we're going to explore and see if we can make some further steps. . . . There are some things that the Cuban government could do.''

Obama spoke to reporters on a sweltering hotel rooftop with a stunning mountainous backdrop, where he defended his policy of courtesy over antagonism and underscored that his administration was not behind an alleged plot to assassinate President Evo Morales of Bolivia.

Obama came under fire for appearing too cozy at the summit with Venezuelan President Hugo Chávez, who was part of a diplomatic full-court press here to urge a change in Cuba policy.

REMITTANCES

After meeting most of his fellow 33 heads of government who make up the Organization of American States, Obama said strides had been made, particularly with Venezuela and Cuba.

Now, he said, Havana must take additional actions if it's serious about improving relations with Washington.

''They could release political prisoners. They could reduce charges on remittances. . . . It turns out that Cuba charges an awful lot; they take a lot off the top,'' Obama said, referring to a total of 20 percent in fees. ``That would be an example of cooperation where both governments are working to help Cuban families and raise standards of living in Cuba.''

Obama noted that he was struck by how many of the leaders at the summit deeply appreciate Cuba's overseas medical brigades. The United States, he said, does not serve its own interests if its only contact with nations is through military and drug interdictions.

"I think that's why it's so important that in our interactions not just here in the hemisphere but around the world, that we recognize that our military power is just one arm of our power, and that we have to use our diplomatic and development aid in more intelligent ways so that people can see very practical, concrete improvements in the lives of ordinary persons as a consequence of U.S. foreign policy.''

Last Monday, Obama lifted the last restriction that kept Cuban Americans from visiting their families on the island more than once a year and limited how much money they could send. At this weekend's summit, leader after leader urged him to do more, such as ending the U.S. trade embargo.

''We all love Cuba here, are friends with Cuba, and hope the United States will be, too,'' Chávez said.

Obama defended his support of the embargo and acknowledged that he spoke against it ''eons ago'' when he was a state senator in 2004.

''The Cuban people are not free,'' Obama said. ``And that's our lodestone, our North Star, when it comes to our policy in Cuba.''

Obama's three-day visit to the region ended on a disappointing note in Port of Spain when only Trinidadian Prime Minister Patrick Manning signed the summit's final declaration.

Several leftist countries, led by Venezuela, refused to sign it because it excluded Cuba and did not adequately address the global economic crisis. Others followed suit, because it was not a unanimous document.

''It would have been much better if all the presidents had signed the final declaration,'' said Edwin Carrington, secretary general of the regional economic bloc Caricom. ``It shows commitment.''

CALLED A SUCCESS

Experts said the summit was a success nonetheless, particularly for Obama. He entered the hemispheric stage Friday under a barrage of tirades about Washington's dubious history in Latin American politics.

Although heavy on symbolism and lighter on concrete results, Obama came out ahead by illustrating that he was willing to listen and be polite to his adversaries, experts said.

''Obama's realism stands out. He is willing to recognize that Cuba wants to talk, and that talks might be worth pursuing,'' said longtime Cuba-watcher Philip Peters, vice president of the Lexington Institute in Virginia. "He's pointing to a step Cuba could take to get the ball rolling.''

Lowering remittance fees would be easy for Cuba, Peters said, because that exchange-rate policy began as retaliation for former President George W. Bush's decision to limit how much money Cuban Americans could send their relatives.

''The summit had a lot of symbolism, but symbolism that sends a positive message: U.S. national security interests are better met, not with confrontation, but with action,'' said Florida International University's Eduardo Gamarra, who followed the summit closely as a political consultant for Dominican President Leonel Fernández. ``Obama played this very well.''