The Magpies had already snapped up Martin Dubravka, Fabian Schar, Ki Sung-yueng, Kenedy and Yoshinori Muto to boost Rafael Benitez's options, but the Spaniard has remained in pursuit of another striker.
With the club's opening Premier League fixture against Tottenham Hotspur less than a week away, the decision on the players' behalf not to speak to the media will come under widespread scrutiny if they uphold their stance.
"We are concerned. Everyone in the dressing room was really upset with our performance and with how things are going, but we will try to change things in the next 10 days".
Newcastle United players are refusing to co-operate with the media in a dispute with the club over bonuses.
Formerly of Malaga, Las Palmas and Zenit St Petersburg, Rondon is on the move after three years with West Brom, as he was always unlikely to stay and play in the Championship following their relegation.
Newcastle have been chasing Rondon all summer but only wanted to take the striker on loan.
The Baggies fans will forever be in my heart. I have a lot of confidence in this group of players but they know we have to do something if we want to improve the competition between players.
'It's an honour to be here and I'm excited to get started with my team mates, ' he said.
Newcastle boss Rafa Benitez is hoping to complete the £20m signing of Danny Ings from Liverpool after the former Burnley forward expressed his desire to leave Anfield in search of consistent game time.