"We are very disappointed," said NZC chief executive Justin Vaughan, aggrieved that Vincent started negotiations with ICL before his New Zealand contract lapsed on May 31, and without seeking a release.
"He flagrantly breached his contract. I have expressed to Lou and the New Zealand Cricket Players' Association how disappointed I was that Lou breached his contract.
"Lou obviously doesn't want to play for New Zealand any more, he's off for financial reasons only."
Vincent, 29, has become the 10th New Zealand representative to join the ICL.
The 23-Test veteran, who is waging a well-publicised battle with depression, would forever have "a black mark next to his name" after negotiating a contract without NZC's knowledge, Vaughan said.
Vincent, who was not available for comment, quit all forms of cricket before Christmas shortly after returning from unsuccessful tours of South Africa and Australia.
He then publicly admitted he was battling depression.
Vincent, who made a century on his Test debut against Australia in 2001, averaged 34.15, while his one-day average from 102 internationals was 27.11.