Think nothing of it

Think nothing of it.

 and Don't give it another thought.; Don't give it a (second) thought. 
1. You're welcome.; It was nothing.; I was glad to do it. Mary: Thank you so much for driving me home. John: Think nothing of it. Sue: It was very kind of you to bring the kids back all the way out here. Alice: Think nothing of it. I was delighted to do it.
2. You did no harm at all. (A very polite way of reassuring someone that an action has not harmed or hurt the speaker.) Sue: Oh, sorry. I didn't mean to bump you! Bob: Think nothing of it. Jane: Ihope I didn't hurt your feelings when I said you were too loud. Bill: Don't give it a second thought. I was too loud.
See also: nothing, of, think

think nothing of it

do not apologize or feel bound to show gratitude (used as a polite response).
See also: nothing, of, think

think nothing ˈof it

(spoken, formal) said as a polite reply when somebody has thanked you or said sorry for something: ‘I’m terribly sorry for all the trouble I’ve caused you.’ ‘Think nothing of it.’
See also: nothing, of, think