But European Club Association chairman Andrea Agnelli, sat next to Uefa president Aleksander Ceferin at a press conference, said: "It's possible for earlier implementation".
German news magazine "Der Spiegel" claimed to have documents which showed Europe's biggest clubs planning for a Super League from 2021.
At a September executive meeting, UEFA said it would introduce video assistant referees (VAR) in August at the Super Cup, then the Champions League qualifying playoffs.
The head of European football has dismissed proposed plans for a breakaway European Super League as "a fiction or a dream" that will never happen.
"We are fully engaged with Uefa in shaping the game going forward".
"I can confirm we have never seen, never discussed, never been involved in the creation of this document [about a Super League]", said Agnelli.
"We are delighted as clubs for that and we thank Uefa for the work they've been putting together".
Speaking at a joint UEFA and ECA press conference in Brussels on Tuesday, Ceferin said the European governing body's refereeing chief Roberto Rosetti has been leading efforts to make sure UEFA's pool of referees are ready for VAR and all "technical aspects" have been addressed.
Ceferin continued: "Financial Fair Play should be a more solid tool and at the moment the rules are too weak in some areas". "Participation stays, and everybody will have an opportunity to compete in every European competition".
A third European competition to run alongside the Champions League and Europa League is set to be confirmed next month.
He noted that it was UEFA's duty to safeguard the heritage of football in Europe, saying that they had to think about upcoming markets, not only keeping them safe.