The French international, 28, was heavily linked with a transfer to the Premier League club over the summer.
"I had a talk with Newcastle's coach and we found an agreement," Gomis told TV show Canal Football Club. "Then there were talks with Lyon, there was a first offer - which was refused and then a second one, which was accepted.
"Newcastle then came back to me and asked me to make an effort on wages - but I never asked anything as it was my club which wanted to transfer me, so the effort had to be made by Newcastle or Lyon."
Gomis scored 18 goals in all competitions for Lyon last season.