You can report it but I would be extremely surprised if anything actually happens. I really doubt that the police will bother to chase it up and if they do I doubt they'll find much to press charges. There is a non-emergency number you can use to report things.
There's a lot of stuff that happens in our society that shouldn't happen and it's totally wrong, but unfortunately, for whatever reason it's not taken seriously and no one wants to deal with it. I had a man approach me at a bus stop late at night on my own (with no one else at the bus stop and no nearby shops) and he said some really inappropriate/creep/scary things to me and about my appearance and that he wanted to kiss me - he literally leered at me and got in my personal space. He showed me a tag attached to his ankle, saying he was not long out of prison and I just basically tried to ignore him and moved away but he kept talking and moving towards me. I thought I was in luck when the bus arrived but apparently I had the wrong type of ticket and I had no change on me - I told the bus driver that I was being harassed and he told me I needed to pay or get off. I had to get off the bus and the man was still there. I felt really unsafe so I started walking and I ended up walking half way home on my own at night because of that. I reported the incident to the bus company and they wouldn't take responsibility and the police said they had nothing to go on.
So although people like to say 'oh get over it etc' - unless you've actually experienced it, STFU because it's not pleasant at all and it can be terrifying as female when you're on your own and a man starts saying things to you. I'm really not surprised that the OP walked away considering there was a group of men.Plus these men start thinking they can get away with it and then they might start doing it on their own and not with a group. Remember that you're no safer in a crowd than I was on my own - people ignore things because they don't want to get involved (bystander effect, I think it's called) so if you feel unsafe just leave.
Basically, you did the right thing walking away OP. I'd report it to McDonald's and to the Police but don't be surprised if nothing gets done - it shouldn't be allowed to happen and it's totally wrong but the authorities just don't give a **** unfortunately. I just don't go to places that make me feel uncomfortable on my own anymore. If I have to be somewhere alone at night I let people know when I'll be back etc and I always take spare change now and if I walk into a place and don't like the vibe I walk straight out, IDGAF what people think of me now - if someone makes me uncomfortable in any situation I spin of my heel and get out of there and immediately call someone just to talk about the weather - whatever - just so someone knows where I am etc.