As much as they are right, it's none of their business. I don't agree with free-trade agreements at all; in fact, all agreements between nations are unnecessary and dangerous. However, those countries attacks on our policy are an example of why interventionism isn't the best solution.
Firstly, free trade agreements are, in the words of Senator Paul, "managed trade". They don't actually mean free trade, they just mean that the government has more control over trade to whatever country (and vice-versa). Real free trade doesn't require a treaty, it just requires the government to step back.
Secondly, America should be promoting a non-interventionist foreign policy. This means that we would remove our troops from all areas abroad, end all current treaties we are part of, and avoid any entangling alliances in the future. Remember, if you are allies with one person you are enemies with someone else, but if you are allies with no one then no one is your enemy (on the world stage). Granted, that statement only applies if the US achieves one other goal: real free trade. Free trade and economic interdependence are the only ways the achieve peace and stability between nations. The British and the French fought for hundreds of years until they started implementing free trade. Now they still hate each other, but they're not expressing it with a bayonet.
When countries trade with one another and are dependent on each other they will not fight each other, UNLESS one of the countries imposes regulations or starts interfering in their affairs. This is exactly what America has done, and is the reason why so many countries can't stand us. If we ended all alliances, got our troops out (remember, we still pay to defend places like Germany), and traded with everyone, we wouldn't be in this foreign policy mess that we are in now.
So, avoid the free trade agreements as well as conflicting alliances. As much as America needs to do it (oh, and dear god we do), other countries need to as well. Then we'd all be better off.