"Iran is standing by its previous position and expects the Europeans to take positive measures," Iranian Foreign Mminister Kamal Kharazi was quoted as saying by the official news agency Irna.
"Iran's position in the negotiations is clear and we want to resolve the problem with an approach that guarantees our interests."
Kharazi complained that "until now the Europeans have not taken any clear or constructive decisions to resolve the problems whereas Iran has".
Senior officials from Britain, France and Germany were to meet Iranian counterparts in Brussels on Tuesday for talks aimed at averting an escalation of a stand-off with Tehran over its nuclear programme.
The Brussels talks aim to prepare the way for negotiations in Geneva on Wednesday, led on the European Union-side by the trio's foreign ministers and EU foreign policy chief Javier Solana.
The current crisis surrounds Iran's demand to back away from a November 2004 deal under which it agreed to suspend its uranium conversion and enrichment activities, which Washington believes conceal its nuclear armament intentions.
Iran insists its bid to master the full nuclear fuel cycle, including uranium enrichment, is merely aimed at generating electricity and is a right for any country that has signed the nuclear Non-Proliferation Treaty.