"We can't feel sorry for ourselves," Jarvis told the club's official website. "We need to stay positive and make sure we are working extremely hard as we did at Liverpool and get that positive result we need to kick-start our season.
"It's definitely time to roll our sleeves up and fight. That's exactly what we need to do.
"However we get the three points, it doesn't matter what we do, we just have to get them and get ourselves up the league."
West Ham return to Premier League action on Saturday when they welcome fellow strugglers Sunderland to Upton Park.