I have found working solution. But for me it look ugly.
uint8_t command = 0x55;
uint16_t u16Temp = 0;
u16Temp = GPIO_ReadOutputData(GPIOA)&0xFF00;
u16Temp |= command;
GPIO_Write(GPIOA, u16Temp);
Is there better way to output 8bit value to PORTA without affecting other pins?