I can see a book developing here on street defence strategy.
1 ) I solved that dilema a couple of times with a stern confident look, and saying "I REFUSE to fight you, I DO NOT fight people. However, if you attack me, I WILL defend myself." ( must engage opponent in conversation and a pint )
2 ) If I was a street fighter one method I would try is to get the attacker's shirt pulled over their head tying up their arms. This is where this thought process is coming from. ( must only fight opponent wearing a shirt )
3 ) Get behind your attacker and take him down ( when he is not looking of course )
4 ) It is the first duty of an Aikidoka in a confrontation to protect their attacker from harm ( if you are that good )