The Hammers travel to Anfield after suffering a 1-0 defeat to Crystal Palace on Monday evening, but Tomkins is optimistic that his side can come away with at least a point.
"It was a disappointing game on Tuesday," he told the club's official website. "Looking back at it, we could have scored from a couple of chances and obviously the goal we conceded was disappointing from our point of view.
"We just have to be upbeat and keep going, because that's all we can do. There is a game on Saturday at Liverpool. We got a good result [a goalless draw] at their place last season and hopefully we can get more of the same."
West Ham are 17th in the Premier League table, with 10 points from their first 14 games.