Barack Obama has hit back at Israel's prime minister, insisting the United States had not "given anything away" in new talks with Iran, as he defended his continued push for a diplomatic resolution to the dispute over Tehran's nuclear ambitions.
The US President said he refused to let the talks turn into a "stalling process", but believed there was still time for diplomacy.
His assessment, delivered at the close of a Latin American summit in Colombia, came after Israel's prime minister Benjamin Netanyahu said the US and world powers gave Tehran a "freebie" by agreeing to hold more talks next month.
Mr Obama retorted: "The notion that somehow we've given something away or a 'freebie' would indicate Iran has gotten something. In fact, they've got some of the toughest sanctions that they're going to be facing coming up in just a few months if they don't take advantage of these talks."
In a news conference later, Mr Obama warned Iran: "The clock's ticking."
Winding down his three-day trip in the port city of Cartagena, Mr Obama also sought to offer hope for fresh start with Cuba, saying the US would welcome the communist-run island's transition to democracy. There could be an opportunity for such a shift in the coming years, he said.
Standing alongside Colombian president Juan Manuel Santos, Mr Obama also proclaimed a free-trade agreement between their countries as a win all-around, even as US union leaders condemned it. Mr Obama announced that the trade pact could be fully enforced next month, now that Colombia had enacted a series of protections for workers and unions.
The president had hoped to keep his role in the Summit of the Americas focused on the economy and the prospect of the region's rapid economic rise as a growth opportunity for American businesses.
But that message was quickly overshadowed by an alleged prostitution scandal involving Secret Service staff who were in Colombia to set up security for Mr Obama's trip. The president said he expected a full, rigorous investigation of the allegations, and would be angry if the accusations turned out to be true.
As Mr Obama met Latin American leaders, negotiators from the US and five other world powers were in Turkey for a fresh round of nuclear talks with Iran. While previous talks have done little to dissuade Iran from moving forward on its nuclear programme, diplomats called the latest negotiations constructive and useful. Both sides agreed to hold more talks in Baghdad at the end of May.