The Championship club want to keep all of their attackers, including Said Benrahma and Bryan Mbeumo.
But Watkins, who is part of the "BMW" trio, could move if he gets a Premier League offer.
And the Daily Mail says Villa will offer 26-goal-man Watkins a route into the top flight.
Crystal Palace are also interested in Watkins as they try and revitalise their tepid attack.
Benrahma is also attracting Premier League interest, and Villa are keen on him as well.
But Brentford hope to keep the same squad for next season and push again to get promotion.