Negotiations with prime minister-designate Fuad Siniora, who has been attempting to form a government since 30 June, collapsed last week after Aoun's Free Patriotic Movement insisted it be given the Ministry of Justice to put in place reforms and an anti-corruption drive.
"After [Siniora's] decision to revisit talks and consider the composition of the cabinet ... we have returned to the principle of participation," Aoun told reporters after a meeting with his movement on Saturday.
"We hope that this situation will speed up the formation of the government because Lebanon needs a responsible regime and we cannot regain time lost. I hope that the government will be formed rapidly and that we will participate in it," he said.
"There are several questions still up in the air. We have examined the principle of returning to participation, but many things must be discussed away from the media."
Aoun, who has become one of Lebanon's foremost Christian political leaders, did not say whether Siniora has promised his party the Justice Ministry.
That is a demand that the Future Movement's Saad al-Hariri, who leads the biggest bloc in Lebanon's 128-member parliament with 37 seats, had deemed "impossible".
Al-Hariri said his Future Movement needed to control the ministry amid the ongoing enquiry into the 14 February murder of his father, the former prime minister and tycoon Rafiq al-Hariri.
"I hope that the government will be formed rapidly and that we will participate in it"
Free Patriotic Movement leader
This prompted Aoun to tell al-Hariri that his bloc of 21 MPs would not be taking part in the government.
Lebanese President Emile Lahoud had asked Siniora on Wednesday to take up talks again with Aoun.
However, a key difficulty remains for Siniora, with the Shia movements Hizb Allah and Amal demanding the foreign ministry.
Aoun's decision to revisit participating in government came after Washington and Paris insisted on the rapid formation of Lebanon's new government following parliamentary elections that ended last month.
Lebanese media said some further delay is inevitable, however, because the government cannot be formed before next Wednesday when parliament speaker Nabih Berri returns from an official visit to Algeria.