The nation of Tupalow is outraged that the Republic of Za has repeatedly violated international human rights laws. As a result, Tupalow has decided not to export goods to or import goods from Za. What is such an action called?

This would be called a trade embargo: the prohibition on a trade with the country that the embargo was imposed on.

A recent high-profile embargo is the embargo on Russian products by many European countries, which was imposed in response to the invasion of Crimea