Lonely kid

So this last weekend we spent a lot of time with family and some friends which a lot of them have kids the same age or close to the same age as my daughter. Well I noticed that every time she would try and play with the other kids they would run away from her or yell at her to go away. I told them that they weren’t being nice which got ignored but I’ve noticed it happens a lot with her and other kids and I feel horrible cause I can see that it upsets her, it got so bad this weekend that she actually quit trying to play with the other kids and just sat by herself and played. Up till two weeks ago she was an only child and I’m a stay at home mom and I feel like this is my fault that she can’t make friends or gets left out. Any advice on what I can do?