Probably from a- (“a-”) +‎ moca (“mockery”) +‎ -ar.

• IPA^(key):

amocar (first-person singular present amoco, first-person singular preterite amoquei, past participle amocado)

1. (intransitive) to bug; to pester

   Synonym: amolar

   • 1889, A Monteira, number 6, page 43:

     Antes de rubir ó puleiro, non fan máis que cacarexar qu'han facer i acontecer, pro non se ve outra cousa dempois máis qu'os benfeitos que reciben tódo-los que teñen a sorte de ll'axudar nas falcatrúas, pr'amocar ós que non son do pau, e nas trécolas pra conquerir sona co cacique maor, que dende Madril diuta disposiciós d'intrés particolar prós seus nagocios.

     (the councillors) before climbing onto the perch do nothing but cackle about what they'll do and what will be, but then you don't see anything other than the benefits received by all who have the fortune to help them in their frauds, to pester those who don't belong to the same suit, and the tricks to gain fame with the great cacique, who from Madrid dictates dispositions of particular interest for his own business.

• moca

• Antón Luís Santamarina Fernández, editor (2006–2013), “amocar”, in Dicionario de Dicionarios da lingua galega (in Galician), Santiago de Compostela: Instituto da Lingua Galega
• Antón Luís Santamarina Fernández, Ernesto Xosé González Seoane, María Álvarez de la Granja, editors (2003–2018), “amocar”, in Tesouro informatizado da lingua galega (in Galician), Santiago de Compostela: Instituto da Lingua Galega
• “amocar” in Dicionário Estraviz de galego (2014).
• Rosario Álvarez Blanco, editor (2014–2024), “amocar”, in Tesouro do léxico patrimonial galego e portugués (in Galician), Santiago de Compostela: Instituto da Lingua Galega, →ISSN