The United States on Monday ruled out Iran’s call for a lifting of sanctions, saying that the Islamic republic must first address concerns over its nuclear program in “concrete” ways, AFP reported.

Over the weekend, Iran held talks with major powers, for the first time in 15 months. The European Union’s foreign policy chief, Catherine Ashton, later said the talks have been constructive and that the sides will meet again in Baghdad on May 23.

Ashton said future talks will be guided by the “principle of a step-by-step approach and reciprocity.”

On Monday, Iran’s Foreign Minister Ali Akbar Salehi said that the entire dispute could be quickly resolved if the West shows goodwill by easing sanctions.

“We are ready to solve all issues very quick and easily, even in the Baghdad talks, if there is goodwill,” Salehi said.

“It is possible to discuss in the talks percentages of uranium enrichment,” he added. “If they guarantee supplying us with fuel of various enriched levels, the case will be different.”

In response, U.S. State Department spokesman Mark Toner told reporters, “No one’s talking about any sanctions being reversed or canceled at all.”

He added, however, that the United States was ready to look at incentives in return for progress from Iran.

“We want to see Iran come up with some concrete proposals moving forward and that if that were to happen, we would look at ways — Cathy Ashton’s statement said as much — to reciprocate,” Toner was quoted by AFP as having said.

On Sunday, President Barack Obama said that nothing had been “given away” to Iran during the talks in Istanbul. Obama warned Tehran that the clock was still ticking to reach an agreement over its nuclear program.

Obama’s comments came in response to comments made by Israeli Prime Minister Binyamin Netanyahu, who said during a meeting with U.S. Senator Joe Lieberman, “My initial impression is that Iran has been given a freebie. It’s got five weeks to continue enrichment without any limitation.”

“The notion that we’ve given something away or a freebie would indicate that Iran has gotten something,” Obama said in Colombia. “In fact, they got the toughest sanctions that they’re going to be facing coming up in a few months if they don’t take advantage of those talks. I hope they do.”

Toner also denied any “freebie” for Iran on Monday, saying, “We’ve got the strongest sanctions in history against Iran right now, and they’re going to get stronger as we move into the summer.”