The memorial was spray-painted in pro-Palestine graffiti overnight, marking the fourth time a war memorial has been hit in recent months.
One slogan read: “Israeli bombs desecrate Aussie graves and kill thousands in Gaza.”
Another said: “Free Gaza.”
RSL National Greg Melick condemned the latest incidence, reiterating calls those responsible “should face the full force of law”.
“Our War Memorial honour those who have sacrificed to protect and preserve the freedoms that all Australians enjoy and daubing of protest slogans is nothing short of despicable,” he said.
“It is dishonorable in the extreme to use war memorials as a platform for protest.”
Melick argued the “defilement” of memorial sites did nothing to advance their cause.
“They are desecrating the memory of those who served and sacrificed to give them the right to protest, a right that does not exist in many other countries,” he said.
“Australians should respect that right responsibly and with respect.”