However, the European Union has set no specific timeline for Iran, saying on Friday there was "no real limit," and that the EU was in "no rush" to have a response "in the next 24 hours".
Manouchehr Mottaki, the Iranian foreign minister, also said on Thursday that there was no deadline and his country had already replied.
Western powers accuses Iran of pursing nuclear weapons however Iran says it programme is purely for peaceful purposes.
The incentives package offered by the US, Russia, China, Britain, France and Germany includes pledges on civil nuclear energy, trade, finance, agriculture and high technology if it freezes uranium enrichment.
If Iran accepts the package, there would be pre-negotiations in which Tehran would add no more uranium-enriching centrifuges and, in return, face no further sanctions.
The package was offered to Iran by Javier Solana, the European Union foreign policy chief, in June.
The US had recently softened its stance over the nuclear crisis in Iran and sent William Burns, a high-level US diplomat, to Geneva to encourage those a deal.
The US had previously refused to sit down with Iran until it suspended uranium enrichment.
It has already imposed three rounds of sanctions on Iran over its nuclear programm, targeting state banks, imposing visa bans on officials and also enforcing measures against companies seen as linked to the programme.