"Let the believers not make friends with infidels in preference to the faithful—he that does this has nothing to hope for from God—except in self-defense" (3:28).
"Believers, do not make friends with any but your own people. They will spare no pains to corrupt you. They desire nothing but your ruin. Their hatred is evident from what they utter with their mouths, but greater is the hatred which their breasts conceal" (3:118).
(Infidels are 2nd class)
First of all, what is an infidel? IIRC Muslims believe "Infidel" means someone who is hostile to Islam, not merely someone who doesn't agree with it, in which case that would make sense...
In any case, it says "In preference to the faithful" it doesn't mean you can't associate at all.