At least four people from the group Renegade Activists ascended the building on Thursday, as police, media and supporters watched from below.
"We declare to the Australian government, we will continue to unmask and resist the US imperial, hegemonic and capitalist interests you devote yourself to," one protester yelled from the rooftop.
"Australia continues to enable and commit war crimes as lackeys to our powerful friends."
One of the banners stated "from the river to the sea, Palestine will be free"
The phrase has been condemned by the prime minister and coalition who claim it supports a one-state solution where Israel wouldn't exist.
However, it has also been used by pro-Palestinian protesters and Labor senator Fatima Payman - who controversially used the phrase to defy the prime minister - to call for justice and freedom in occupied territories while still supporting a two state solution.
The West Australian was suspended from the Labor caucus after she crossed the floor to support a Greens motion on Palestinian statehood and vowed to do so again in the same circumstances.
She has described feeling isolated from her fellow party members, raising questions over her future political career.
Jacob, a representative from the activist group, praised Senator Payman.
"She's doing what she has been employed to do and that is represent the best interests and the aspirations of her constituents," he told AAP.
"What the Labor Party is actually telling us is that they would prefer people to bulls*** about how they feel, than to speak the truth.
"And I think that uncovers the Labor Party more than anything else."
Opposition home affairs spokesman James Paterson called for an investigation into how the protesters were able to defy security measures to climb onto the roof at parliament.
"This is serious breach of the Parliament's security, the building was modified at great expense to prevent incursions like this," he wrote on social media site X.
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