"Rebuke the beasts of the reeds (qaaneh), the herd of bulls with the calves of the peoples, till everyone submits himself with pieces of silver (presents, tribute). Scatter (lit. 'He scatters') the peoples who delight in war" (Ps.68:30, NKJV).
In today's passage Yahweh tells His people to rebuke those enemies who appear like "beasts of the reeds" (possibly crocodiles living by the side of a river or even lions), representing, powerful and fierce monarchs or those in power, who are likewise the "herd of bulls". The "calves" are the nations or peoples whom these sovereigns rule, wild and lawless like their masters.
This is pretty much the situation believers find themselves in throughout the nations. They are oppressed by hostile rulers and are surrounded by their wild and lawless subjects. But when they come up against us, we are commanded to rebuke them in the Name of Yah'shua (Jesus) until they submit and pay tribute in whatever form Yahweh desires of them.
When the Israelites left Egypt, the Egyptians showed them with their wealth so that they would leave and take their curses and plagues with them. Likewise when the true power of Elohim (God) is with believers, because they are submitted and walking in divine tavnith (pattern) in obedience to the mitzvot (commandments), trusting in Messiah, then those who have oppressed them will beg them to separate themselves from them so that they might find a measure of peace, or pay them tribute, showing proper respect and defference.
The effects of the precipitous action on the part of those hostile to Yahweh's people is that they are scattered, literally (as in scattered troops) or more generally in the sense that their concerted actions are broken apart are brought to naught. Those who have delighted - in their own perverse way - of coming against Yahweh's people may, if they are wise, and after they have been brought to the edge of ruin and to utter despair, seek for the their prayers, as Job's friends did of Him...if they are repentant. If they are not, then the direst of consequences must of necessity follow.
I have witnessed Yahweh's hand fulfil this very scriptrue several times in my life and with each new assault has come near disaster for the enemies. We ought to walk in this confidence, trusting in Almighty Elohim (God), not fearing but claiming the promises of such Scriptures. As the enemy gets bolder, using the ever greater powers of sovereigns and governments granted to them by their "calves", so he must be the more roundly defeated and be made to pay with "pieces of silver".