Ahead of their Europa League quarterfinal second-leg clash at Eintracht Frankfurt tonight, the Holland international said Spurs players were fully supportive of their manager.
With the aggregate score locked at 1-1, many are claiming the result could decide the position of Postecoglou.
But Van de Ven said: "We all still have the trust in the gaffer and still have trust in the way he's playing, so tomorrow we want to win the game of course for him, but also for us, also for the club, and also for the fans.
"It hasn't been a really good season, but it's a big game for us and of course we want to achieve something special this season. I think this is the best way to do it.
"Of course, we have also some Premier League games to play, but if we want to win some silverware, of course it has to be the Europa League, and we have to win this game to go to the next round. It's a big game for us, yeah."
Asked what Postecoglou has told his players ahead of tonight, Van de Ven admits they're under no illusions over how big the game is.
"That it's a big game for us, but it's also a game like every week," he said.
"We have to play our best football, we have to play the way we want to play, we want to create as many chances as we did in the last game against them.
"Hopefully we can win this game and go to the next round."