Telling you what you should use is impossible without knowing what you're trying to say. However, both come and came can make an appropriate sentence here. As currently written, only one of your examples is grammatical. As originally written, before your edit, that was also true - but you swapped which one was grammatical. There's also a third and fourth option I'm going to throw in to help illustrate the point, and it may be that you actually want one of those.
If I come, I will call you.
This is making a conditional statement about the future. If clauses referring to the future use the present tense, but the action that is to be done in that event should be grammatically future. This is saying that, in the event that you come in the future, you will call them. This is essentially a conditional agreement or promise.
If I came, I would call you.
This is using the past to express a hypothetical. It looks like past and past, because would is the past form of will, but things aren't that simple. It has essentially the same meaning as the next choice:
If I were to come, I would call you.
Some people I've known consider this the 'correct' version of the previous option, because it expresses a hypothetical condition in the way they think is formally correct. It is certainly more formal than the previous.
If I had come, I would have called you.
This is making a statement entirely about the past. It implies that you didn't come, because it is asserting that you would have called if you had done so.
