The former Arsenal midfielder has signed with Villarreal amid charges of sexual assault in London.
Partey was able to sign with Villarreal after being granted bail.
"The player is currently undergoing legal proceedings. He maintains his innocence and denies the charges against him," Roig said after the 2-0 preseason friendly defeat by Aston Villa.
"The club upholds the presumption of innocence, and it will be the responsibility of the English courts to clarify the facts. We have spent years demonstrating our values with all kinds of activities.
"We respect the presumption of innocence and, of course, condemn any type of violence, whether inside or outside of football.
"At this moment, Partey is as innocent as the rest of us here. A fundamental right like this must be respected."
On claims he was whistled by Villarreal fans, Roig said: "The English whistled Partey. Not the Villarreal fans.
"I wouldn’t like our own fans to whistle at players on our team. We must stand with the team and respect the presumption of innocence. He is not a convicted player.
"We must be cautious and wait for justice. Let’s not judge prematurely. Thomas has the right to do his job until there is a conviction."