The actor's character Ryan Connor has an on-off relationship with Sian Powers (Sacha Parkinson), who kissed best friend Sophie Webster (Brooke Vincent) in Sunday night's episode.
Speaking to PA, Thompson commented: "It is good to get your teeth into something like that, it's really nice that they entrust you with something as big as that.
"Obviously it's never happened on the Street before, so for them to say you're going to be the first involved with it is a really nice thing."
Asked whether it is every man's dream to see two girls kissing, he replied: "I don't know, is it? It's a bit weird - they're colleagues of mine. I'm like, 'I don't wanna see that!'"
Sophie and Sian's growing affection for each other is expected to be a long-term plotline.
