Wa `alaykum as-salamu wa rahmatullahi wa barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister, it is really a great pleasure for us to receive your important question. We also commend your eagerness to be well knowledgeable about Islam and its teachings.
First of all, we would like to stress that Islam forbids targeting civilians by killing or by kidnapping or taking them as hostages, or inflicting any kind of harm on them. There are other rules on how to deal with combatants.
The Prophet (peace and blessings be upon him) said: “Do not kill a woman, a child, an old man, or a monk in his monastery; do not cut down trees.” In another version of the hadith, he is reported to have said, “…do not kill traders or farmers.”
All of these hadiths mean that it is strictly forbidden to target civilians by killing or kidnapping or taking them as hostages, or inflicting any kind of harm on them.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and an Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states,
Islam is opposed to terrorism in all forms and shapes. Terrorism is terrorism, whether it is done by states or suicide bombs targeting civilians or civilians.
Humanity needs to value the sanctity of life – a central teaching of all great religions. So it is time that men and women of conscience stand united and oppose all aggressive wars and acts of terrorism, whether the state sponsored or those perpetrated by individuals, whether done under the pretext of democracy or wrong conceptions of religions.
Allah Almighty knows best.