President Hassan Rouhani warned Tuesday that middlemen who have circumvented sanctions will need to "think of another job" as a potential final nuclear deal brings changes to Iran's economy.
The remarks, at a ceremony in Tehran ahead of Labour Day on Friday, signalled Rouhani's intent to tackle a black market that has thrived in Iran after official trading routes were cut off.
Although sanctions plunged the economy into recession and hurt most of the population, some Iranians have amassed fortunes from smuggling foreign goods from Turkey, Iraq and Gulf states.
"Sanctions busters should now think of another job," Rouhani said.
"With the final agreement -- which if the other side has serious determination will be possible in the coming months -- production and the economic situation will be much better."
Iran and the five permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- plus Germany have begun drafting a final nuclear accord which is due by June 30.
The agreement is intended to ensure the wholly peaceful nature of Iran's nuclear activities in exchange for the lifting of a slew of international sanctions imposed since 2006.
"To increase production we need... new technology, competent management, investment and the presence of entrepreneurs," he added, stressing the need to attract "domestic and foreign capital".
Rouhani had made a similar warning at the same time last year, saying "a small, fringe group is very angry" about sanctions being lifted under a nuclear deal "because they will suffer losses".
Since the signing of an interim agreement in November 2013 that eased the sanctions regime, foreign trade delegations have visited Iran with a view to resuming trade after a final agreement.
About two dozen American businesspeople visited Tehran last week and a large delegation from Switzerland, the first in 10 years, arrived Sunday for four days of consultations with politicians and economists.
Large foreign companies in the oil and automotive industries have also made contacts for a return to Iran if sanctions are lifted.
Rouhani in his speech also cited the importance of equality between men and women at work.
"There should be no bias between men and women. We should create equal work opportunities," he told Labour Minister Ali Rabii at the event.