Villa remain hopeful that the 24-year-old Belgium international, who reportedly has a £32.5million buy-out clause in his current contract, will sign a new deal amid speculation that Manchester United and Liverpool could launch bids to land him this summer.
However, Cascarino has voiced concern over the player's lack of form last season before the arrival of new manager Tim Sherwood, and believes he should be sold if his head has been turned.
The former Republic of Ireland international told the Express and Star: "You're fortunate to play for clubs like Villa and I believe if the player doesn't want to be there, then you have to look elsewhere.
"I don't like keeping players who don't want to play for you
I'm not convinced clubs are sure at £32million.
"He came back after injury and looked a shadow of the player for six months
He looked nowhere near the Benteke that ripped teams apart and took on teams on his own at times, and then he got back into the fold once Tim got the job and looked the Benteke of old.
"But that's only over a four-month period."
Benteke arrived at Villa in a £7million switch from Genk in August 2012 and scored 23 goals in his first season in English football.
However, he managed only 11 the following season and, as injury struck during the last campaign, had contributed just three by the time Sherwood replaced Paul Lambert in February.
Benteke then added a further 12 - 11 of them in the league - in his last 13 games as the club dragged itself out of relegation trouble.
Source : PA
Source: PA