"The first thing is to confirm his capture," court spokesman Fadi El-Abdallah told AFP.
"What we are going to do is wait for official confirmation from the authorities that a suspect wanted by the ICC has been arrested."
Florence Ocara, a spokeswoman for ICC prosecutor Luis Moreno-Ocampo, added, "We are coordinating with the Libyan ministry of justice to ensure that any solutions with regard to the arrest of Seif al-Islam is in accordance with the law."
A senior official on Libya's National Transitional Council said earlier today that Seif, Gaddafi's one-time successor, was arrested in southern Libya.
NTC justice minister Mohammed al-Allagui declined to give any details.
The ICC issued warrants on June 27 against Seif as well as his father and Abdullah al-Senussi, Gaddafi's intelligence chief, on charges of crimes against humanity in crushing anti-regime protests.
Moreno-Ocampo predicted on November 9 that Seif's arrest was just a matter of time, adding, "Seif will face justice, that's his destiny."
A week earlier, the prosecutor told the UN Security Council that the ICC had "received questions from individuals linked to Seif al-Islam about the legal conditions attaching to his potential surrender."