The Doctor had obviously frightened the poor girl so he put his hands up slightly in a non-threatening manner to show her that he wasn't there to harm her. 

"Yeah, sorry," The Doctor said in reply to the girls question. "I tend to wind up in places and not know where I am quite a bit." He took a couple of hesitant but friendly steps towards her, shoving his hands back into the pockets of his trench coat as the girl went on to question who he was. 

"Oh, I'm just a traveller." The Doctor replied, smiling slightly. "Peter Jones, eh? We'll, that's a first. Tell me, have you noticed anything...strange going on around here lately?"