Can genital rubbing lead to pregnancy if there was no ejaculation or penetration? The head of the penis was rub against the vagina without ejaculation

May not. It is unlikely get pregnant by just rubbing genital but no ejaculation.
Pre-ejaculate. Most likely, this activity would not cause a pregnancy, but, there is the chance that the fluid that comes out before you actually ejaculate (a pre-ejaculate) can contain some sperm and if that sperm makes its way into the vagina, than it could cause pregnancy if all the correct conditions and timing is optimal. Use birth control, including condoms for sti prevention. Best wishes.