I had never realised this to be such a problem until some mums were hostile when discussing the Muslim parents at my dcs school.
As I was friends with them, and had play dates and also spent time with them, sitting together on rugs at picnics in the park, I never knew there were people who dismissed muslims because they weren't exactly the same as them, and didn't seem remotely interested in putting in the time to develop the relationships.
We were always welcomed into their homes, and fed delicious food!
Having said that, I made sure my DH wasn't here, when we had their girls over, ate vegetarian food, and whenever we ate out at a pizza restaurant, one of the Muslim DHs felt more comfortable sitting at a separate table.
I think the militants of any culture give them all a bad name. With Islamic people's it's difficult to reach out, as they don't want to be harassed for the actions of the militants, and with the English, there can be a lack of education about how women Muslims who are devout conduct themselves(with modesty and gentleness- not pushing them selves forward).
Maybe offer to sit together at a local park and chat with the Muslim mums while the kids play together, OP. Making friends can be a slow process, but there are many shared values and experiences.
I like my Muslim friends, my Irish, Jewish and Sikh ones too, even some of my English ones aren't too bad!!
Don't forget to smile. 