Rangers now trail leaders Celtic by three points with the league race ending on Thursday evening.
Smith's men play their game in hand against St Mirren on Monday but must also make up a goal difference of seven.
"We just have to concentrate on winning both games," added Smith.
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"There is still a bit of football to be played. Teams are not just going to turn up and allow Celtic and Rangers to win.
"Motherwell showed that today. They played with pride and put in a great effort and I'm sure it will be the same with St Mirren, Aberdeen and Dundee United.
"It was in our own hands, but it's not now and that is disappointing - but we just have to get on with it."