Bill Murray filmed a cameo in the 'Ghostbusters' reboot because he wanted to give it his blessing.

The 64-year-old actor - who played Peter Venkman in 'Ghostbusters' and 'Ghostbusters II' - admitted he thought long and hard about working on director Paul Feig's new movie and took on a small role so that everyone would know he approved of it.

Speaking about the film, which stars Kristen Wiig, Melissa McCarthy, Kate McKinnon and Leslie Jones, he explained to Vulture: ''I thought about it for a very long time. Like, many, many months. No, that's not right. I was seriously thinking about this for years, really.

''It kept eating at me, and I really respect those girls. And then I started to feel like if I didn't do this movie, maybe somebody would write a bad review or something, thinking there was some sort of disapproval [on my part].

''I like those girls a lot. I mean, I really do. They are tough to say no to. And Paul is a real nice fellow.''

Bill won't reprise the role of Peter in the new movie and is instead believed to be playing a medium who tries to discredit the work of the ghostbusters.

He added: ''They were incredibly nice to ask me, and I really enjoyed being there. They have such a jolly group, and they are going to have great success with this project. I didn't want to overshadow [them] or anything, and I feel really good about it.''