One must keep in mind the deplorable state of catechesis in the Catholic Church, since for several decades, CCD was quite vague and taught little of substance (it seems much better now in many places). Perhaps it's that way for many Muslims as well, who don't know that Mary is considered one of the four righteous women of Islam.
That said, one goes a long way from ignorance to aggression, and this story is disturbing:
A man was kneeling in prayer before the statue of the revered Madonna, with the photograph of a loved one in hand, in the small chapel of St. Barnabas in Perugia (Italy), when he was attacked by five “immigrants.”
The first thing they did was rip the photo from his hands. Next they unleashed their hatred against the image of the Virgin Mary. They broke the statue to pieces and then urinated on it.
For more this topic -- specifically how Christians and Muslims actually view Mary quite differently, go here.
UPDATE: And here is an example of Christians doing what Christians do best -- forgiving and praying for their persecutors. While, unfortunately, the bishop dismisses any religious motivation for the damage caused (how can he know) this is an opportunity to explain the organic creation and care for these little shrines (thanks to SuburbanBanshee):
The whole point of Italy’s neighborhood chapels and shrines (already an old custom in St. Francis of Assisi’s time) is that anybody can stop by these tiny places for prayer or quiet, and the whole neighborhood takes care of them voluntarily. Many are hundreds of years old, some over a thousand years old. Some are indoors, some are outdoors. They hurt nobody and cost no public money.
In this case, it’s a lot more recent. In 2000, a previously vacant and abandoned lot – a depressing eyesore near high-rise apartment buildings without green space – was bought and turned into a tiny park, garden, and outdoor chapel by local Catholic parishioners. The “Parco della Maddonnina” (Little Madonna Park) was then made available to everyone for walks, playground sports, board games, reflection, and prayer, at the price of absolutely free. It brought up property values and made the locality a better place to live and work.