Uriarte and Athletic have been angered by constant questions for Williams about his future while with Spain.
Williams and his teammates have fielded questions consistently about the winger's future at San Mames.
He barked: "Nico, a footballer very committed to Athletic Club, has been subjected to a bombardment of questions about his future in an excessive and uncontrolled manner, when he is concentrated to compete at the Euros by the Spanish Football Federation, who have not known how to protect him.
“Respect among all the actors that make up football is a fundamental basies, or that is how we conceive it at Athletic Club, which does not have the formula of subjecting players with contracts to other clubs to public pressure to try to sign them.”