Aoun, a Maronite Christian politician, is a political ally of Lebanon's Iran-backed Shi'ite Muslim group Hezbollah. The United States, which classifies Hezbollah as a terrorist organisation, arms and trains Lebanon's army.
"The unilateral U.S. withdrawal from the nuclear agreement (in May) will have negative repercussions for security and stability in the region," Aoun wrote on Twitter, his first public comment on the accord.
"Lebanon considered (the deal) a cornerstone for stability in the region, helping make it an area free of weapons of mass destruction," Aoun's office said in a statement summarising a meeting between him and Iranian foreign ministry official Hossein Jaberi Ansari.
Aoun said he welcomed the commitment of other countries to continue with the deal.
U.S. President Donald Trump withdrew Washington from the deal in May, calling it deeply flawed, and has reimposed stringent U.S. sanctions, heaping pressure on other signatories including major European allies to follow suit.
European powers have reaffirmed their commitment to the accord and say they will do more to encourage their businesses to stay engaged with Iran, though a number of firms have already said they plan to pull out to avoid U.S. penalties.
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)