"We have agreed to suspend it and we are studying the modalities of a suspension," foreign ministry spokesman Hamid Reza Asefi told AFP.
Asked if this meant enrichment activities were still going on in the country, he replied: "Implicitly, yes".
Earlier, Asefi had said he believed that a halt to enrichment had been implemented, but then retracted the comment.
The acknowledgement that work was still under way came five days after Iran vowed to cooperate with International Atomic Energy Agency (IAEA) demands during an unprecedented joint visit by the foreign ministers of Britain, France and Germany, Jack Straw, Dominique de Villepin and Joshka Fischer.
An IAEA deadline for the Islamic republic to meet a series of demands expires this coming Friday, and the UN's nuclear watchdog's board of governors is to meet to evaluate Iranian compliance on November 20.
During Tuesday's talks with the European Union's big three, the Islamic regime agreed to sign an additional protocol to the Non-Proliferation Treaty (NPT) that allows tougher checks by the IAEA.
Iran says it will formally state its intention to sign before the agency meets in November, but has nevertheless agreed to work within the framework of the protocol by allowing unlimited IAEA inspections pending signature and ratification of the protocol.
The country also agreed to make a full declaration of its activities, and on Thursday handed the IAEA a report with information about its controversial nuclear programme.
Iran's ambassador to the IAEA, Ali Akbar Salehi, said Friday that Iran in its report to the watchdog admitted that it had failed to meet international nuclear safeguards commitments but he again denied that Iran was seeking nuclear weapons.
Iran was asked to cease uranium enrichment after IAEA inspectors found traces of highly enriched uranium during previous visits. Iran says the traces came into the country on imported equipment.
But officials here have emphasised that any suspension of enrichment -- said to be one of the most difficult issues during Tuesday's talks -- would only be temporary.
"We are suspending enrichment temporarily," Asefi said, adding that he hoped the IAEA board would make a reciprocal gesture of "trust building" in return.
"It is natural that we will not give up our right to peaceful nuclear technology. This is the legitimate and natural right of Iranians. Suspension is a temporary matter," he said.
In return for Iranian compliance, Britain, France and Germany said the Islamic republic could "expect easier access to modern technology and supplies in a range of areas".
Diplomats said that opened up the possibility of Iran receiving nuclear fuel from overseas, thereby keeping the sensitive fuel cycle -- and the risk of its misuse -- out of Iranian hands.