"If the Europeans don't take any measure within the 60-day deadline, we will take new steps," ISNA quoted Kamal Kharrazi, the head of Iran's Strategic Council on Foreign Relations, as saying.
Kharrazi was speaking after meeting Britain's Middle East Minister Andrew Murrison, who visited Tehran for "frank and constructive" talks and to call for urgent de-escalation in the region, according to the Foreign Office.
Tehran said in May it would reduce compliance with the nuclear pact it agreed with world powers, in protest at the United States' decision to unilaterally pull out of the agreement and reimpose sanctions last year, Financial Tribune reported.
Iran added that it would start enriching uranium at a higher level unless the European signatories to the deal protect its economy from renewed US sanctions within 60 days.
Kharrazi, a former foreign minister, said the Europeans should know that Iran is "serious" in implementing its announced plans after the deadline passes, if no tangible measure is taken by them to ensure the country reaps the economic benefits assured by the accord.
Britain, France and Germany have set up a special purpose vehicle called the Instrument in Support of Trade Exchanges or INSTEX, a conduit for non-dollar trade with Iran, in an effort to shield at least some of Iran's economy from sweeping US sanctions. However, it has yet to be launched.
Positive Step
It would be a positive development if they put resources in INSTEX and make trade possible, Kharrazi said.
"We have to see in the next two week whether they only make promises or take practical steps."
He said the British minister repeated European officials' previous statements that the financial mechanism will be launched soon and that they support the nuclear deal.
The head of Iran's Strategic Council on Foreign Relations noted that Europe is expected to act independently of the United States.
Kharrazi said he told Murrison that "serious steps" should be taken by the British government to improve Tehran-London relations.
The Iranian official also cautioned Britain against drawing "hasty conclusions", saying that such an approach does not help defuse tensions.
Kharrazi made the comments in reference to Britain blaming Iran for recent attacks on tankers in the Sea of Oman, saying that no other state or non-state actor could have been responsible.
Iran denies any involvement.