If a friend blows you off because you didn't give them money, they are not a friend and you should be glad to be rid of them. Seriously. The surest way to damage a friendship is to actually give the money. Debts between friends are more damaging than anything else, including refusing the loan or gift in the first place.
The next time someone asks you for money simply say you're not comfortable with it because of what it might do to your friendship. That does seem to be your first concern. Beyond that, say you've had to tighten your belt, too, and you've very sorry that you're unable to help.