Larijani did not, however, say whether parliament would be given a vote on the agreement, which provides for lifting sanctions on Iran in exchange for rolling back Tehran's nuclear programme.
Last month, parliament announced the makeup of a 15-member panel largely composed of conservative lawmakers to review the historic deal.
"The review by committees will be completed in early Mehr (the Iranian month between September 23 to October 22) and the representatives of the people will give their opinion," Larijani was quoted by the ISNA news agency as saying.
Some Iranian MPs want the government to submit the deal as a bill for parliament to vote on.
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But the government and nuclear negotiators believe such a vote is against Iran's national interests as it would turn voluntary commitments into legal obligations.
Formal oversight of the accord rests with Iran's Supreme National Security Council, which is headed by President Hassan Rouhani and reports to Khamenei.
Larijani, who backs the agreement reached with the West, said this week during a visit to the United States that "there will be heated discussions and debate in the Iranian parliament" about the deal.