West Ham co-chairmen David Sullivan and David Gold have issued a message to Hammers' fans and say the club will "turn our season around".
Slaven Bilic's side are in the Premier League relegation zone after losing five of their opening six fixtures and failed to reach the group stages of the Europa League after a 2-1 aggregate defeat to Astra Giurgiu.
Southampton left the London Stadium with a 3-0 win on Sunday to add to West Ham's early season woes but Sullivan and Gold have called for unity from everyone associated with the club and say things will improve.
"There is no question that this has not been the start to the season that we were looking for but rest assured we are doing everything we can to fix the situation," a statement on the club's website said.
"The facts are there for everyone to see. We know we are letting in too many goals and not scoring enough, but be assured we will sort the problems out. There have been factors which have contributed to the poor start with injuries to key players and some key decisions which have gone against us.
"But we are not going to make excuses and know that Slaven and his team will be working even harder on the training ground this week to get things right. We have got to remain positive. These are the same players that helped us enjoy such a memorable final season at the Boleyn Ground.
"We know this is a difficult time for our supporters at the moment but we want to thank you personally and wholeheartedly for staying with the club. We will turn our season around. These are tough times but as Mark Noble said over the weekend, this is the time that the West Ham United family needs to come together."
The statement went on to thank West Ham fans for their support at the new stadium after moving from the Boleyn Ground at the end of the season.
"We can't thank you enough for the impeccable way you pulled together and supported the team yesterday," the statement said.
"Our fans have always shown over the years the amazing support they have for the team and we have no doubts they will get behind the players even more over the coming weeks.
"We stated last week that we would be putting measures in place to make the London Stadium experience something everyone can be proud of and we would like to thank all our supporters for their support in this regard.
"Supporters can rest assured that we will not be slowing our efforts despite the match against Southampton being completely trouble-free, and we will not stop working until everyone feels they have a stadium to be proud of - on and off the pitch.
"We would like to thank all fans for their incredible support and continued cooperation."