The Dockers have issued a strong statement in response to speculation the AFL will trial new rules in games this year.
Fremantle chief Steve Rosich has declared his club won't be used as guinea pigs for proposed rule changes that have sharply divided players, coaches and fans.
And in another strong intervention on Thursday, St Kilda coach Alan Richardson warned the league against pursuing "exhibition games" after the Saints put the changes to the test during an AFL-supervised training session.
The AFL's competition committee has agreed to at least half a dozen rule changes aimed at reducing congestion after meeting in Melbourne on Wednesday.
AFL football operations manager Steve Hocking has refused to outline the specific alterations that will be recommended to the AFL commission and executive.
Starting positions at centre bounces and forward and defensive-50 stoppages, a longer goal square and the elimination of prior opportunity were among the rules trialled by the Saints in a 20-minute scratch match at Moorabbin.
The AFL has left the door open to trialling the changes during late-season games involving teams that are no chance of making the top eight.
Fremantle round-21 clash with Carlton had been earmarked as a potential option but Rosich on Thursday said the Dockers would not agree to participate.
"If it got to the stage that a trial was proposed for one of our games in 2018, Fremantle's position is that we would not support that occurring," Rosich said in a statement.
Rosich added he had spoken to Hocking, who reiterated trials were more likely at reserves-level and any AFL test game would require approval from competing clubs and the AFL Commission.
Richardson was also uneasy about the Saints' potential involvement in the trials.
"That would worry me ... just going out to play an exhibition game," Richardson said.
"That would be something that I feel uncomfortable about."
Richmond coach Damien Hardwick and Collingwood counterpart Nathan Buckley have both expressed support for AFL-level trials, although their respective ladder positions means neither team would be asked to play in such a game.
A major hurdle for the league would be finding a way to ensure the draft order is not compromised.
Carlton appear certain to finish bottom of the ladder and receive the No.1 draft pick but just four points separate the 14th-placed Bulldogs from 17th-placed Suns.
At least six but potentially as many as 12 recommendations will be made for the AFL commission to consider for endorsement at meetings in August and September.
Any changes set to come into force next season will be announced by October.