The Hammers fell 2-0 at home as Brentford won through goals from Igor Thiago and Mathias Jensen.
Afterwards, Nuno told Sky Sports: "Today was a disappointing evening because it was a disappointing performance. It was not good enough.
"I think we had a good spell. In the first 15/20 minutes we had a good spell and there's a chance and then after that we got ourselves in trouble. Brentford were aggressive."
On the anger of the home support, Nuno continued: "We have to realise, I honestly believe that our fans are concerned more than anything. The silence is about being concerned of the situation. They are concerned and we can feel it.
"That feeling passes to the players and transforms themselves to anxiety because we had precise situations that quality players like we have shouldn't have, so it's a mix of everything that in the end on the pitch with the players becomes harder. Now, it's fair enough to say that we have to be the ones to pull the fans together."
On fans leaving before the final whistle, he said: "We need it but it's up to us. It's up to us to connect with out fans. We know that if they see what's going on on the pitch they will support us. It's up to us now."
Asked when West Ham will improve, Nuno added: "Tomorrow. Realising that every day is important to improve this situation it has to start tomorrow. Responsibilies, commitment, hardowork and a little bit more conscious effort. We need it."