Economic sanctions, isolation by international community. There needs to be consequences, but simply launching a cyber counterattack is not a good solution.
It's also not workable. I mean, what kind of counter cyber attack would it be? It sounds pedantic but it's true that two wrongs do not make a right, and the USA should always hold the moral high ground. We lose it the second we launch a cyber attack.
Also I doubt a counter cyber attack would even be an effective deterrent. Again, what would it look like? What would be the purpose? It would be lame compared to what they did to us.