Yes, Miguel, two choices are possible. 1) I've just called her. The version using the present perfect for events in the recent past is commonly used in British English. It is also correct in American English but is more likely to be used to stress the fact that something happened in the recent past. 2) I just called her. This version using the simple past for events in the recent past is common in American English. The listener/reader understands by context that the speaker/writer is referring to the recent past.

two are possible depending on what tense is used