El Ghazi put out a pro-Palestine statement on his social media handles on Sunday.
The 28-year-old only joined Mainz as a free agent last month after leaving PSV Eindhoven.
He has played three games for the club so far but his next appearance for Mainz remains uncertain.
A post from the Bundesliga side read: “Mainz have relieved Anwar El Ghazi of his training and matchday-related duties.
“The decision comes as a result of a since-deleted social media post from the 28-year-old that appeared on Sunday evening.
“In the post, El Ghazi took a position on the ongoing conflict in the Middle East that was deemed unacceptable by the club.
“Prior to making this decision, the club and the player had engaged in an in-depth discussion.
“Mainz respect the fact that there are varying perspectives on the decades-long, complex conflict in the Middle East.
“However, the club are distancing themselves from the content of the social media post in question, as it does not align with the values of the club.”
El Ghazi has previously spent time in the Premier League with Aston Villa and Everton.
He has won two caps for the Netherlands national team.
