Griffiths aims to prove Stimson wrong
Gills manager Mark Stimson opted to release the striker - who can also operated wide on the right - rather than offer him a new contract.
But the Gills boss gave Griffiths the chance to come back in for pre-season training and the 31-year-old has been keen to impress.
Talking to the Kent Messenger, Griffiths said: "I know I can do a job.
"I told him (Stimson) by text that when he wants me in to let me know.
"He saw me playing in a trial game and he saw that I'm still capable as I scored twice.
"I like to prove managers wrong. I was on the pitch and he shouted to me, 'I bet you don't score'. I scored twice.
"I played the first match up-front and scored and then in the second game I scored from the right wing. No matter where I'm put, I will score goals.
"There are a few people interested and I could play in the lower leagues on good money but it's not about the money. I'm not going to better myself playing there and I'm just going to sit back and wait for my options.
"I love Gillingham. It's a family club and there is a great rapport there and when I was at the club I felt comfortable."