The Brazil international announced will leave the club when his contract expires at the end of this season in what was an emotional message to fans at the end of January.
Casemiro rallied the side at the time and the club have since pushed into the top 4 as they track down Champions League football.
"It is not time to say goodbye; there are many more memories to create during the next four months.
"We still have a lot to fight for together; my complete focus will, as always, remain on giving my everything to help our club to succeed."
The 34-year-old, who has been a key figure over the past few years has made over 150 games for the Red Devils and Mazraoui has admitted that he will be a huge loss to the club.
“I think the announcement, when I saw it, was like… it was a sad day.
“He brings experience, like crazy. He knows how it is to win.
“He knows how it is, also, the road to win, because he has done it, he has lived it.
“So, yeah, we’re going to miss him a lot in the team, outside of the pitch, inside the pitch, of course.”
Casemiro joined from Real Madrid for £70M in 2022 and has been linked with the MLS and Saudi Pro League as United keep an eye on the likes of Adam Wharton, Carlos Baleba and Elliot Anderson to replace him.