Hasan Rowhani, the country's top nuclear official, did not say explicitly that Iran would resume enriching uranium (search), but he said the country believed activities related to enrichment at the nuclear plants at Arak and Isfahan were "legal."
The International Atomic Energy Agency (search) has questioned work at those two plants, and in a resolution adopted Friday rebuked Iran for past cover-ups in its nuclear program. The document warned the Islamic republic it has little time left to disprove it has a nuclear weapons program.
Iran says its nuclear activities are only for peaceful purposes.
"The work at Isfahan and Arak is not up for bargaining," Rowhani said. "Iran has already made its decision about Isfahan and Arak and the work will continue."
Iran is building a heavy water reactor at Arak, and its plant at Isfahan, which has already been opened, has a nuclear conversion facility to process yellow cake uranium into gas.
Rowhani referred to the process of injecting gas into centrifuges, a major step in uranium enrichment.
"It's not clear whether we will inject gas into centrifuges tomorrow," he said. "Perhaps we may continue suspension ... for some time, but we'll reconsider other measures. In the next few days we will inform the IAEA and our European partners of our decision."
Rowhani indicated other measures could include making centrifuges, which can be used to transform uranium for power or weapons purposes.
Iran, in a deal with European leaders, had agreed months ago to stop making centrifuges in exchange for help with nuclear energy technology.
"We are not committed to that anymore because the Europeans did not respect their commitments. The Europeans had promised to close Iran's nuclear dossier in June," he said.