Earlier on Wednesday, Deputy Spokeswoman for US Department of State Marie Harf said that "if we cannot agree in the final instance to something that meets our bottom line for what we need in terms of access (to Iran's nuclear sites and scientists), we're not going to sign a final deal."
In reaction to Harf's remarks, Afkham emphasized that Iran will not sign any deal with the Group 5+1 (Russia, China, US, Britain, France, and Germany) unless all of the country's concerns are addressed.
"Since the beginning of the negotiations, Iran's viewpoints have been raised clearly and transparently in all cases," Afkham added.
The US spokeswoman had claimed that the two sides are negotiating over the access of International Atomic Energy Agency (IAEA) to Iran's facilities, information, and people.
Her claims came as the Supreme Leader on Wednesday ruled out any request for interviews with Tehran's nuclear scientists, and described it as an instance of "interrogation".
"I would not let foreigners come (here) and talk to the Iranian nation's dear scientists..., who have expanded this wide knowledge to this stage," Imam Khamenei stressed.
Earlier last month, Ayatollah Khamenei had categorically rejected foreign access to the country's "security and defensive" sectors under the pretext of nuclear monitoring.
In their latest round of talks, on April 2, Iran and the Group 5+1 reached a framework nuclear agreement after more than a week of intensive negotiations in Lausanne, Switzerland, with both sides committed to push for a final, comprehensive accord until the end of June.
The framework provides a series of solutions that will be the basis of a comprehensive joint plan of action.