The Wolves were beaten for the first time in the league this season as they went down 26-12 at Craven Park.
"We weren't quiet sharp enough and didn't start the game as we would have liked," Smith told Sky Sports News.
"When you come to Hull KR, it's a tough place to go to. It's a hostile environment unless you take good control but we didn't do that."
The defeat has left Warrington in fourth place in the standings.