(1) Why do the nations rage (noisily assemble) and the peoples plot in vain? (2) The kings of the earth set themselves, and the rulers take counsel together, against the LORD and his anointed saying, (3) "Let us burst their bonds apart and cast away their cords from us." (ESV)
Political unrest reaches maturation in the mobilisation of the masses. The natural sense of justice within the heart of man, fallen and redeemed alike, ferments through the communal conscience of the ordinary people who come out of their homes to 'noisily assemble.'
In Psalm 2 it is important to see that v1 & v2 speak of 2 different groups of people: v1 refers to the masses, the proletariat, v2 to those in authority over them. God is on the side of the masses who are pushed to and past the limits of obedience to corrupt rulers and authorities. He is against those who oppress and exploit.
Even though they may not acknowledge the existence of God, God has requirements of the leaders of nations: fundamentally it is that they govern for the wellfare of the people. So when the psalmist speaks of leaders scheming to 'burst their bonds apart and cast away their cords' he means they are seeking to find ways to abjugate their divinely instituted responsibility of ruling for the good of the people.
The folly of such leaders who would seek to break free from God's parameters for human government is seen in the fact that they consult only with one another, 'they take counsel together.' Such disengagement with the people over whom they rule is a determinative step towards their rebellion 'against the LORD and his anointed.'