Google Merchant Center added a new technical attribute you can use to exclude some or all of your products from displaying in specific countries. The new attribute is shopping_ads_excluded_country and you can use it in your product feeds to communicate to Google to not show these products in specific countries.
This new attribute is only available for Google Shopping ads. Here is the example Google gave in how to use it.
Let's say you select Germany as your primary country of sale, and Austria and Switzerland as additional countries of sale when you submit your product data in Merchant Center. If you later decide that you don't want to advertise a particular product in Austria and Switzerland, you can use this attribute to stop the product from showing there, while still allowing it to show in Germany.
Here are more details in this help document.
Forum discussion at Twitter.
