The Western Australian mining magnate made the offer to ARU officials last week in a bid to prevent the cull of the Perth-based Force as part of the contraction of the mainly southern hemisphere competition to 15 sides for next season.
Pulver said Forrest had tabled a donation of up to A$50 million (30.73 million pounds) to the Australian Rugby Foundation but it had come too late in the day.
"I wish he'd been involved in the process perhaps a little earlier, that would have been helpful," Pulver told reporters in Sydney.
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"We are way down the track having made commitments ... to go to four teams, and having had an EGM where our members voted to go to four teams.
"It's a little late in the process to be making that sort of change."
Rugby Western Australia have appealed the decision to axe the Force at the Supreme Court of New South Wales, which Pulver expected to hand down a ruling next week.
(Reporting by Nick Mulvenney, editing by Peter Rutherford)
