I don't think China will do anything in reply. They will just make verbal condemnations talking about how this is illegal and such but nothing else.
The US has seized sanctioned Chinese shadow vessel CENTURIES, which was moving illegal Venezuelan crude.
The stateless supertanker was falsely flying the Panamanian flag.
The seized Chinese shadow tanker CENTURIES has valid registration in Panama, its licensing is legitimate and up-to-date as of early 2025, and operated by a Hong Kong based firm.
The tanker is not under US, EU or UK sanctions.
China is kinda content with whatever Trump is doing by going after Venezuela and focusing US efforts on the Americas. They don't want Trump to get angry at China and attacking China once again using its so called allies like Japan or PH or Taiwan. They like the US pivot to Latin America.