US Secretary of State John Kerry was set to leave Lausanne on Saturday after almost a week of negotiations which "resume next week", State Department spokeswoman Marie Harf said.
Iran's deputy foreign minister Abbas Araghchi said the negotiations would begin again next Wednesday although where they would be held was unclear.
Kerry would review progress on Saturday "in Europe" with his French, German and British counterparts, Harf said. Iranian television said they would meet in Berlin.
"We've had a series of intensive discussions with Iran this week, and given where we are in the negotiations, it's an important time for high-level consultations with our partners in these talks," Harf said.
Kerry spoke by phone on Friday to Russia and China's foreign ministers, the other two major powers involved in the talks, Harf said.
"Right now more consultation and coordination is needed," Araghchi said.
Overnight US President Barack Obama appealed in a Nowruz (Persian New Year) address to the Iranian "people and leaders" to seize an "historic" opportunity and begin a "brighter future".
Obama said that a "reasonable nuclear deal… can help open the door to a brighter future for you the Iranian people."
"I believe that our nations have an historic opportunity to resolve this issue peacefully — an opportunity we should not miss," Obama said.
In an apparent response, Iranian Foreign Minister Mohammad Javad Zarif said it was the other side that had to make a decision.
"Iranians have already made their choice: engage with dignity," Zarif wrote in a message posted on his official Twitter account.
"It's high time for the US and its allies to chose: pressure or agreement," he said.
"Nowruz is the beginning of spring, and in Farsi, it means 'new day'," Zarif told Kerry in Lausanne.
"I hope this new day will be a new day for the entire world — a new era of greater understanding and peace."