Wolves fought back from 2-0 down to level scores before Lyle Foster struck deep into injury-time as Burnley won 3-2 on Sunday.
Afterwards, Pereira said: "A lot of frustration, because the players worked a lot on the pitch to win the game. But football is football, and sometimes it's very, very unfair. We tried everything to win the game, especially in second half, and in the end we conceded the goal.
“It’s football, we need to understand that the next game is another battle. We lost this one, a very important one for us, because the three points and the win were very important for us to give us the confidence that we need, but it was not possible. Keep working, keep going with our work, and try to be better the next game.”
On the home fans' anger, the Portuguese also said: “It’s normal the frustrations of a result in the last minute, it’s normal that the supporters are frustrated.
"In my opinion the team deserved the support because the players gave everything on the pitch to win the game. We understand because at the end of another defeat it’s difficult to have the balance, but we need them. We cannot fight alone, the players cannot fight alone. We need them, and united and together we can do it.”
On the criticism coming his way, Pereira insists he can handle the knockers.
He added, “I have a lot of experience in football. A few months ago they sang my name. When I arrived here the club was in a very bad position, and we are in the Premier League because together we got it.
"We did fantastic work to be here competing in the Premier League. But I understand it’s football. If you win two or three games in a row everything changes.
“I'm concerned about the team. I'm concerned about winning games, it’s not about me, it’s about the team, about the club.”