His statement in an interview with CNN Philippines today was a departure from his earlier pronouncement that he would "set aside" the ruling because he does not want to impose on China.
Duterte also criticized the United States, saying it did not do anything when China started building artificial islands in the disputed sea.
Duterte, who took office in June, has taken steps to mend relations with China that grew hostile during the time of his predecessor over the long-unresolved territorial disputes.
China has refused to recognise the arbitration tribunal, saying it has no jurisdiction.
Asked under what circumstances he would bring up the tribunal ruling with China, Duterte said: "Yes, when the minerals are already being siphoned out."
If that happens, he said, he will tell China: "I though we're friends? We share economic bounties ... So how about us? I have this title, so what do you think? Don't you think we should talk now?"
"Why raise an issue putting the countries into distress or under stress when you are not going to do anything, when it is you who have the arms?" he added.
China is pitted against smaller neighbors including the Philippines in multiple disputes over islands, coral reefs and lagoons in waters crucial for global commerce and rich in fish and potential oil and gas reserves.
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