Shocking footage showed Japanese police officers grabbing hold of activists and pinning them to the floor among a crowd of people.
The demonstration was reportedly organised by the far-left extremist organisation “Revolutionary Communist League National Committee”, which denounces the meeting of world leaders as a conference of “imperialism for nuclear war”.
Police intervened after a fight reportedly broke out between activists, the BBC reports.
The G7 comprises the US, UK, Canada, France, Germany, Italy and Japan. Eight other nations have also been invited this year.
It came as Joe Biden said the group of industrialised economies is going to "continue to provide humanitarian and security assistance to Ukraine so it can stand strong as long as it needs".
He added that the US today “announced our latest tranche of artillery, ammunition, anti-tank weapons and bridging equipment to help Ukraine succeed in the battlefield.”
In a private meeting with Volodymyr Zelenskyy, Mr Biden says he told him that the US is going to begin training Ukrainian pilots and fourth-generation fighter aircraft, including F-16s jets, to strengthen Ukraine’s air force as part of a long-term commitment to help Ukraine defend itself.
“The past few days have once more underscored how important America’s global leadership is.
“A presumptuous thing for an American president to say. But I think you’ll find if you ask any of my colleagues, it’s true.
“The security and prosperity of the American people are substantially increased by working in concert with our closest allies and partners to build a future of greater economic strength and resilience in a world that is more peaceful and stable.”