The enrichment process produces the material for either nuclear reactors or bombs.
Members of Iran's ruling hierarchy had repeatedly urged the government to cut ties with the IAEA, the UN's Vienna-based nuclear watchdog, if the Security Council imposes sanctions.
"The bill gives a free hand to the government to decide on a range of reactions - from leaving the nuclear Non-proliferation Treaty to remaining in the IAEA and negotiating," Gholam Ali Haddad Adel, the speaker, said during the debate, which was broadcast live on state radio.
The bill said that the government was "obliged to accelerate the country's peaceful nuclear programme and revise its co-operation with the International Atomic Energy Agency based on national interests".
|The parliament's vote came four days after|
the UN agreed to impose sanctions [AP]
The government supported the bill. "This is a very helpful proposal," Hamid Reza Asefi, deputy foreign minister, told the assembly. "I ask legislators to vote for it."
Haddad Adel said that 161 of the 203 legislators in the assembly voted for the bill. Fifteen legislators voted against it, and another 15 abstained.
The Guardian Council, a constitutional watchdog controlled by ultra-conservative clerics, approved the bill very quickly - showing how seriously the ruling hierarchy regarded the move.
The US and some allies accuse Iran of using a civilian nuclear programme as a cover for developing a nuclear bomb. Iran denies this, saying its programme is strictly for generating electricity from nuclear fuel.