Interrupting Shemoneh Esrei to Quiet a Disturbing Child[1]
If a child is disturbing his father during Shemoneh Esrei, the father may not speak to him in order to calm him. However, he is permitted to signal to the child through gestures in order to quiet him, as this is not considered an interruption. If signaling does not help, he may distance himself from the child, or even approach him and quiet him, provided that he does not speak. Some authorities add that making a light sound (such as “nu” or a similar expression) to quiet the child is permitted, as this is not considered formal speech.
With regard to instructing a child during Shemoneh Esrei—such as signaling how to daven properly—it is proper to be stringent and refrain, and instead educate the child after completing the prayer. However, if the child is actively disturbing him or persistently seeking attention, one may be lenient to signal in order to quiet him. In all cases where signaling is permitted, one should ideally first conclude the blessing he is currently reciting before momentarily diverting his attention.
[1] See Machazik Bracha 104:1 in name of Maharam ben Chaviv and Mahariy Molko; Shalmei Tzibur p. 112; Shareiy Teshuva 104:1; Chesed Lealafim 104:4; M”B 104:1; Ben Ish Chaiy Mishpatim 1:7; Kaf Hachaim 104:1; Ketzos Hashulchan 20:20; Chinuch Habanim Kehilchaso Chapter 12:13-16