The £3million misfit, sent out on loan to Brondby seven months ago, revealed he would opt for a move to La Liga where he had two years with Sevilla.
Pukki signed a four-year contract when Neil Lennon signed him in August 2013 and he insists there has been no contact with the club since he left Scotland.
He added: “I have not talked to them. I have not thought of Celtic since I came, I focus only on Brondby. When the time comes I will make a decision, but it is not yet.
“You never know what’s going to happen in football. Even if you have a contract you can be sold. I’m not the type who gets stressed about something. I just live life and I do not think about what will happen.”
Pukki celebrated his 25th birthday on by making his 39th appearance for Finland – managed by former Kilmarnock and Hibs boss, Mixu Paatelainen – in their 2-1 Euro 2016 qualifying defeat to Northern Ireland.
“Georgios Samaras helped me a lot. For training he took it easy but in the games he was always the best player on the field.
“I am better physically because of him. Scotland is not easy. It taught me about dealing with defenders.