The UN Security Council has demanded Iran suspend enrichment activities that some Western governments believe could be used to manufacture nuclear weapons.
The International Atomic Energy Agency (IAEA) is due to report on Iran's compliance at the end of April.
"Whether it is one month or one year, whatever time frames you want to give us, the Iranian nation has explicitly said...that it would not give up its rights on the nuclear issue," Khatami said, according to Reuters. "We will stand up for our rights until the last drop of our blood."
Ahmad Khatami is a member of the Assembly of Experts, a powerful body that exercises limited supervisory powers over Supreme Leader Ayatollah Ali Khamenei. His sermon was broadcast by Iranian state radio.