The 27-year-old was wanted by his country as one of their overage players for the football tournament, which they kicked off with a 1-1 draw against hosts Great Britain at Old Trafford on Thursday night.
However Alan Pardew said Newcastle could not afford to lose the player.
Papiss Cisse: "It was difficult. I wanted to play, but I had a discussion with the manager as soon as I got back.
"I wanted to play for my country, as representing Senegal is very important to me, but the manager said it was best that I rested.
"He said it was better for me, and I understood his decision.
"God willing, I will score a lot more goals this season. I scored 30 goals last season, but I don't set targets for the next season.
"Maybe I will score 30 again - I don't know."