First off, there should be absolutely NO state secrets, and the federal government should never be large enough that it would even need to keep secrets. If our government had remained Constitutionally limited, like it was supposed to be, then this wouldn't be an issue.
Secondly, if our government had honestly been pursuing a non-interventionist foreign policy then we wouldn't have to worry about this at all. We wouldn't need ambassadors in all these countries, and we wouldn't need to be constantly monitoring and forming opinions of foreign dignitaries. If we were non-interventionist, it wouldn't matter because we would still trade with them.
If these leaks are embarrassing for the government, then let them be embarrassed. It will demonstrate that they have way overstepped their bounds when it comes to foreign policy.