The Hammers have found the net twice in their last five Premier League matches following the narrow loss at the KC Stadium.
"The good thing was that we did create chances, we just need to make sure we get a couple of goals from it," Tomkins told the club's official website. "We'll look at it in training, keep working hard and see where that takes us.
"There's not a lot wrong. The goals we have conceded have been mostly from set plays, two free kicks against Everton and the penalty at Hull. It's just one of those things at the moment."
West Ham continue their Premier League campaign this weekend when they make the trip to London rivals Tottenham Hotspur.