It is connected to a motion sensor and don't change quickly.

With relay output or not?

 

With relay output or not?

What do you mean?

 

Relay gives bunch of IOC-type interrupts during short time.

 

Relay gives bunch of IOC-type interrupts during short time.

No, It is an motion detection IC.

 

I'm not able to test this code, but I think that it might do what you want

void myISR(void)
{
    volatile unsigned char lastKnownPORTB;

    asm("MOVF PORTB,w");
    asm("NOP");

    INTCONbits.RBIF = 0;

    asm("MOVF PORTB,w");

    lastKnownPORTB = WREG;
}