With International Atomic Energy Agency (IAEA) inspectors due to report on Iran's activities by the end of May, Foreign Minister Kamal Kharazi said that "we will fulfil our commitments on the nuclear programme."
Speaking in Berlin after talks with German Chancellor Gerhard Schroeder and his ministerial counterpart Joschka Fischer, Kharazi added that "we hope that the European side will also be punctual in sticking to its commitments so this dossier can be closed for good."
He said success would be success for all "and a defeat would mean a defeat for all."
Fischer was one of a trio of EU foreign ministers who last year negotiated an agreement with Tehran under which Iran would allow a tougher IAEA probe to ensure it was clean of a covert nuclear programme.
In return, they dangled a carrot of peaceful nuclear assistance.
No details were made public at the time, but Iran continually refers to the terms of the nuclear Non-Proliferation Treaty (NPT) whereby signatories commit themselves to exchange peaceful nuclear techology.
Iran, however, has yet to be given the all-clear by the IAEA, and has been chastised for failing to disclose key elements of its programme.
Fischer said it was "crucially important" that IAEA chief Mohamed ElBaradei was able to present a "positive" report, based on the inspectors' findings, to the body's board of governors next month.
"If we really want to make progress, then we really must have the complete implementation of the agreement, that is the most important point," he told a joint press conference with Kharazi.
Fischer insisted the EU was keeping to its side of the bargain, notably by not dragging the nuclear issue before the UN Security Council.
"We stand by the agreement but it must be precisely and fully implemented," he warned.
Tehran vigorously denies US and Israeli charges that it is seeking nuclear weapons, and is pressing for its dossier to be taken off the top of the IAEA's agenda during the June meeting -- something that most diplomats say is highly unlikely.