Los Che sit just outside the bottom three on goal difference on the LaLiga table.
With Valencia struggling, there's been claims Corberan has lost the dressing room - which have been rubbished by Beltran.
The Argentine striker told the club's website: "As a group, we're very united. The fans also had a positive feeling, even though it was a real shame not to win against Betis.
"We really thought we could do it. We're holding on to those positive feelings to keep improving: we have a fantastic dressing room, very healthy, and we're all pulling in the same direction.
"I read that we want the coach sacked, which is unthinkable. It would never occur to me to do that."
Beltran added, "From day one, I've said I'd be the first to help the team wherever the coach asked me to. I like being involved with the ball, and it's always nice to receive compliments from the fans for my work and dedication."