The Blancos trainer feels Roberto Palomar crossed a line with his comments, as he branded the Portuguese as "the type of person who leaves after causing a car crash"
The journalist published a story on September 17, where he referred to the Portuguese coach as "the type of person who leaves after causing a car crash".
Mourinho feels Palomar has crossed the line with his choice of words, and has subsequently decided to take legal action against the Spanish newspaper.
"This expression is objectively vexatious and the use of it was completely unnecessary to achieve the objective of the article," a statement from Mourinho's legal representatives reads.
"Mourinho is fully aware of the importance of the right of freedom of expression, and has not and will never take legal action against rightful criticism."
The 49-year-old previously sued El Pais journalist Charles Bouvier for calling him a "Nazi Portuguese".