PFA chief executive Gordon Taylor believes that the reputation of English football has been tarnished by revelations made at the trial of John Terry this week.
The Chelsea captain was found not guilty of racially abusing Queens Park Rangers defender Anton Ferdinand.
However Taylor is concerned that the content of the exchanges between the players may have had damaging effects on the Respect campaign.
He said: "I hope black players do not feel restrained in light of the verdict. Everyone must be vigilant. The players are role models whether they like it or not and they must behave accordingly.
"It has been an unedifying week for football and there is no doubt that the searchlight is on our national sport. We must reinforce the Respect campaign because the image of the game has been tarnished this week."
The FA have yet to conclude their investigation into the incident, which took place during the West London derby last October.
