Iranian nuclear negotiator Saeed Jalili met with Ashton for follow-up nuclear talks.
Ashton presided over two rounds of talks in Kazakhstan between Iran, the five permanent members of the U.N. Security Council and Germany. She said negotiators in April were looking for a "balanced" position from Iran regarding what she described as a "very clear and concise proposal for confidence-building measures."
Jalili described talks with Ashton as "fruitful" saying both sides "will soon hold talks again to set a date for (another) meeting," the official Islamic Republic News Agency reports.
Iran is suspected of pursing the technology needed to manufacture a nuclear weapon, an allegation the Iranian government denies.
Jalili is among hundreds of candidates registered to compete in June's presidential elections. More than 600 candidates registered to replace Iranian President Mahmoud Ahmadinejad, who's ineligible to run because of term limits.
Iran's state-funded broadcaster Press TV reports the Guardian Council will submit its final approved list of candidates by Tuesday.