West Brom boss Tony Pulis insists the club have to move on after Chris Brunt was hit by a coin.
The Northern Ireland midfielder was struck by a missile thrown from the away fans following their 3-1 FA Cup defeat at Reading last week.
Police have made an arrest and are treating the incident as assault while the Football Association is also investigating.
Albion are prepared to ban anyone found guilty for life and ahead of Saturday's visit of Crystal Palace Pulis now wants to look to the future.
"It's happened, you have to deal with it and move on, we have to move on," he said.
"Everyone at the football club and in football was disappointed with it. The whole incident was disgraceful and we don't want to see things like that in our sport.
"People get disappointed when you lose, I accept that, but to do something like that to someone who has played over 300 games is unacceptable. We just have to let the police get on with it.
"Speaking to Albion supporters what really disappoints them is that the club has been shown up for something it isn't.
"Traditionally it's a very honourable club who stick behind their players, team and their club."
Albion are 14th in the Barclays Premier League table but have won just twice in their last 11 games ahead of the visit of Palace, who Pulis left in August 2014.
Fans have started to turn on the head coach after a series of disappointing displays but Pulis accepts the criticism.
"We are no different to any other club. We played at Goodison the other week (a 1-0 win against Everton) and got absolutely pelted when we won the game," he said.
"They pay good money for it. As a manager that is acceptable, to take criticism. If we didn't like it we wouldn't be in it."
Pulis hopes Jonny Evans will be fit following a hamstring injury while Gareth McAuley (hamstring) and Craig Dawson (ankle) have returned to training.