Manchester City possess a 13-point advantage and still have a game in hand due to last weekend's EFL Cup final triumph over Arsenal on Sunday.
Since Sir Alex Ferguson's retirement as manager in 2013, the club have failed to finish higher than fourth, and they face a battle for second place as arch rivals Liverpool, whom they face on March 10, are two points behind them.
"I think obviously we've been second for quite a while and that needs to be our bare minimum," Sky Sports News quotes Smalling as saying.
"The fact we get to play Liverpool at home as well I think is a big advantage. If we can separate ourselves from Chelsea and Liverpool and work our way up then we can do that, but I think that's our [objective] first and foremost."
United will face Crystal Palace at Selhurst Park on Monday in the league.