Nick Cullen, of the Climate and Migrant Justice Organising Group, said the demonstration reflected a shared struggle across movements.
"We joined this march because we must stand together against the deepening hostile environment, far right violence, and the erosion of climate action," he added.
"Today showed that in these challenging times, our communities are stronger and more powerful when we come together."
John Hilley, of the Gaza Genocide Emergency Committee in Glasgow, said the fights for human rights and environmental protection were inseparable.
He added: "We must act together and with urgency against the same corporate and political forces behind those existential threats."
The war in Gaza was triggered by the Hamas-led attack on southern Israel on 7 October 2023, when about 1,200 people were killed and 251 others were taken hostage.
Since then, more than 69,000 people have been killed by Israeli attacks in Gaza, according to the Hamas-run health ministry, whose figures the UN considers reliable.