Catalysis of the reaction: (8Z,11Z)-5-(pentadeca-8,11,14-trien-1-yl)resorcinol + S-adenosyl-L-methionine = (8Z,11Z)-5-(pentadeca- 8,11,14-trien-1-yl)resorcinol-3-methyl ether + H+ + S-adenosyl-L-homocysteine.
5-n-alk(en)ylresorcinol O-methyltransferase activity