Fight in the way of Allah against those who fight against you, but begin not hostilities. Lo! Allah loveth not aggressors.
Qur'an 2:190
To those against whom war is made, permission is given (to fight), because they are wronged;- and verily, Allah is most powerful for their aid.
Qur'an 22:39
Therefore if they withdraw from you but fight you not, and (instead) send you (Guarantees of) peace, then Allah Hath opened no way for you (to war against them).
Qur'an 4:90
But if the enemy incline towards peace, do thou (also) incline towards peace, and trust in Allah: for He is One that heareth and knoweth (all things).
Qur'an 8:61