The correct option is
C can't
In the given sentence, 'but' indicates that the second clause contradicts the first one. Thus, the second clause has to make a claim against the first clause. The first clause says that the subject can kick the ball and in order to contradict this fact, the second clause has to mean that the subject does not have the ability to play football. Thus, the answer has to indicate this.
Option A is incorrect. 'can' indicates that the subject has the ability to play football. Thus, it does not convey the correct meaning and is not the correct answer.
Option B is incorrect. 'am' gives the subject the quality of being but, in the sentence the subject is being given an ability. Thus, using 'am' does not make sense. Also, the phrase 'I am play' makes no sense.
Option C is correct. 'can't' means 'does not have the ability to'. Thus, it indicates that the subject does not have the ability to play football. It conveys the correct meaning and is the correct answer.
Option D is incorrect. 'will' indicates that the subject is going to play football and does not talk about the subject's ability to play. Thus, it does not convey the correct meaning and thus, it is incorrect.