The ex-Tottenham Hotspur forward has enjoyed a mixed start to the Russian season, scoring once in three games and also putting through his own net.
Bilic told reporters: "I understand perfectly that this has not been the best period for him but Roman knows I expect more from him.
"It is because I know how strong a forward he is, Roman is a top level goalscorer. I see that he works without sparing himself, the goals will come."
Lokomotiv play their fourth match under Bilic in the Russian Premier League on Saturday against Alania Vladikavkaz.