The 30-year-old Gabonese midfielder, who joined Esteghlal from Saudi Arabian club Al-Riyadh in August 2024, is going to pen a new deal.
Ndong has been a member of the Gabon national football team since 2012.
He started his playing career in Tunisian club CS Sfaxien in 2011 and has also played for English sides Sunderland and Watford.
Esteghlal will represent Iran in the 2025-26 AFC Champions League Two.