Please understand the context. Some people had promised to fight aggression but they did not fulfill their promise.
61:1 All things in the heavens and all things on earth are striving to manifest the glory of God and to fulfill His plan. For, He is the Almighty, the Wise.
61:2 O You who have chosen to be graced with belief! Why do you say what you do not do?
61:3 It is despicable in the Sight of God that you say what you do not do.
61:4 Truly, God loves those who fight in His cause in columns as if they were a rock-solid wall. [Fighting in His cause, see 2:190, 60:8-9]
61:5 (The people of Moses frequently said what they did not do, so) Moses had to tell them, “O My people! Why do you hurt me, even though you know that I am God’s Messenger to you?” But when they kept deviating, God let their hearts deviate. God does not guide those who keep drifting away from their word. [Faasiq = One who drifts away - from? - depends on the context. 61:3]