The Orlando City marquee, 32, has 89 international caps to his name, but only seven since the 2010 World Cup.
And after being left out of Brazil coach Dunga's latest squad, which sees the South American powerhouses play France and Chile in friendlies, Kaka said he is still hungry to be competing in Russia.
"It is in three-and-a-half years and if Dunga needs me I'll be ready to play in the national team," Kaka told the Daily Mail. "It is a real motivation for me."
Kaka scored the first goal for start-up franchise Orlando City in their MLS bow on March 8, earning them a momentous 1-1 draw with New York City FC.
And the former Milan and Real Madrid star said he harboured no wishes to return to Europe, despite some of his friends trying to lure him to the Premier League.
"They joke with me saying, 'Come and play for Chelsea or Arsenal' but I am so happy here in Orlando," the 2007 Ballon d'Or winner said.
Coached by Jose Mourinho in Spain, Kaka said he loved playing under the Portuguese tactician - who incidentally followed the midfielder to La Liga.
Kaka departed Milan in 2009, before Mourinho left Inter in 2010 to arrive at The Santiago Bernabeu.
"His ambition for victory sets Mourinho apart," Kaka said of the two-time UEFA Champions League-winning coach.
"He wants to win every game, so he prepares all the smallest details; in training, at the game, everything. I loved to work with him.
"He tries everything to extract the best from the players, to push them. This is what he can do better than anyone else."
