The contracted players have been withdrawn from the competition in order to rest ahead of their November tour of England and Ireland and next year's World Cup in France.
However, the Bulls had used lock Victor Matfield to help them with their line-out problems ahead of their semi-final clash with Western Province last week.
This led to a complaint from Western Province and they have now been told they must not use the players in training ahead of the final.
"We received a letter saying we will not be able to use any player this week," Bulls coach Pote Human said.
"It is a bit strange, but we have to abide by the letter we have received."