Villa on Monday confirmed they had released Darren Bent and Enda Stevens but offered terms to Vlaar, whose contact expires at the end of the month.
The 30-year-old, however, appears to have his mind set on a move away from Villa Park.
“I want to maximise my career and I think I can go a step higher,” he said.
“I will look at it and go quietly.”
Vlaar had hinted in April that he was happy to stay following the appointment of Tim Sherwood and the club’s FA Cup semi-final win over West Brom.
“Things have changed for me in the past few months since Sherwood took over,” he said. “It’s been a hard season for me with all the injuries. Now I just want to play and be important for the team. This helps – you can trust me on that.”
Manchester United are among the clubs to have been linked with Vlaar this summer, and Derby new boy Bent believes his former team-mate is capable of playing at the top level.
“He has had a frustrating year with injures, picking up little niggles here and there, but as people saw at the  World Cup, when he is on top form he is one of the best defenders in the world,” Bent told talkSPORT.
“He is solid, he is quick, he has got everything to be a top defender.
“It is a bit disrespectful to say he is bigger than Villa, because Villa is a big club, but it his decision and he has got all the attributes to be one of the best centre-backs in the world.”