It's a bit of a tricky one. I take your point about the skills, abilities and experience; however, it was a conditional offer and you haven't met the conditions. It's a bit like a 'buy it now' - you can't expect to come back later and buy it at that price, if that makes sense. That said, you can state your interest and commitment in the new role and hope they still grant you the pay rise.
I think when you do this you are marking your own card with your bosses. They may well give you the original increase still but there will be a fair bit of doing it through gritted teeth which they'll hopefully be professional enough for that not to show.
What you do have on your side is that some people would have accepted the condition but gone for the interview hoping the current job didn't find out. So you have behaved with integrity on that side. I'd emphasise this (without acting like they should be grateful!)
My employer made a conditional offer appointed me to a new role at the top of the pay scale. The condition was that I didn’t go along to a interview with another company. I really wanted to go for the interview so I declined the offer. I was unsuccessful at interview so I’m now back having to negotiate my salary with my employer. I feel that my skills, abilities and experience to do my new role have not changed. Any advice on negotiating?