By Hira Humayun, Ramin Mostaghim and Jennifer Deaton, CNN

(CNN) -- Iran's parliament has passed a bill that would boost uranium enrichment to pre-2015 levels and block nuclear inspections if sanctions are not lifted, in the wake of the assassination of a top nuclear scientist.

Iran's more moderate president, Hassan Rouhani, whose government signed the landmark 2015 nuclear deal with world powers, had opposed the bill, arguing that it would undermine diplomacy.

Iran's government has repeatedly called on the US to restore the agreement which President Donald Trump withdrew from in 2018. President-elect Joe Biden has promised to return to the pact.

The "Strategic Action Plan to Counter Sanctions" parliamentary bill demands that European parties to the deal lift sanctions on the country's oil and banking sectors by February, threatening to suspend nuclear inspections by watchdog International Atomic Energy Agency and withdraw from the Nuclear Non-Proliferation Treaty, according to Iran's state-run Press TV.

The bill also allows for Iran to begin enriching uranium at 20%, well over the limits set in the nuclear deal, if economic sanctions are not lifted.

Iran's parliament overwhelmingly endorsed the bill on Tuesday, according to Press TV, with 251 out of 260 lawmakers voting in favor of it. Iran's Guardian Council then ratified the bill on Wednesday, according to the parliament's mouthpiece, ICANA. The Guardian Council is a 12-member vetting body that reviews legislation adopted by the parliament.

At a televised cabinet meeting prior to its ratification, Rouhani warned that if the bill became law, it would be detrimental to the diplomatic process aimed at reviving the nuclear pact.