Rowhani, a moderate-conservative cleric who was declared winner of Iran's presidential election on Saturday, also described as unfair and unjustified sanctions imposed against the Islamic republic over the nuclear issue.
"The idea is to engage in more active negotiations with the 5+1, as the nuclear issue cannot be resolved without negotiations," Rowhani said, referring to the UN Security Council's five permanent members plus Germany.
The 64-year-old's victory raised hopes of an easing of strained ties with Western nations, but he used his first news conference on today to rule out a halt to his country's controversial enrichment of uranium.
There were "many ways to build trust" with the West, he added, as Iran would be "more transparent to show that its activities fall within the framework of international rules."
Rowhani has previously vowed to restore diplomatic ties with the United States, which cut relations in the aftermath of the 1979 seizure of the US embassy by Islamist students.
He was helped to victory in Friday's election with the backing of reformists, with thousands of people taking to the streets to celebrate and world powers expressing cautious optimism.
Failure to reach an agreement in the negotiations has seen the Islamic republic repeatedly slapped with international sanctions that have hit its economy hard.
"Threats and sanctions are not effective" Rowhani told reporters today.
"The sanctions are unfair, the Iranian people are suffering, and our (nuclear) activities are legal. These sanctions are illegal and only benefit Israel," said Rowhani, who is due to replace President Mahmoud Ahmadinejad in early August.
Western powers and Israel believe the programme is being used to develop an atomic bomb, but Tehran has always insisted it is for purely peaceful purposes.