Environment Minister Greg Hunt is seeking information about claims the Japanese whaling fleet attacked activists in the Southern Ocean.
At the same time he has called for both parties to abide by international law.
Environmental group Sea Shepherd says two Japanese harpoon ships attempted to disable its vessel The Bob Barker on Sunday night, by trying to jam its propellers and rudders with steel cables.
The ships also repeatedly crossed the bow of The Bob Barker at close range, violating the International Regulations for Preventing Collisions at Sea, the group says.
Mr Hunt said there had been conflicting reports about the incident, and he was seeking additional information about the stand-off.
"My message is very clear to all parties - all sides must absolutely abide by international maritime law," he told reporters in Canberra on Monday.
It is the second time this month the activist group claims it has been attacked by the whalers.
Mr Hunt ordered an investigation into earlier claims a Sea Shepherd vessel in New Zealand waters on February 2.
