Don't think so - you'd be charged if they let it go through and you went overdrawn, and for other failed transactions like bounced cheques, but not for a refused debit card.
If a transaction is declined, there is definitely no charge. But don't assume that if you have insufficient funds that your card will be declined. I believed that was the case until a couple of months ago. I stupidly didn't keep an eye on my bank balance, made a purchase, went £5.00 overdrawn and was then charged £25.00 by Abbey.