Zakharova dismissed the agreement as "null and void," calling it insignificant and lacking substance, Russian media said.
She argued that Britain's involvement reflects its long-standing ambition to secure a foothold in the Azov-Black Sea region.
She stated that there is no legitimate basis for Ukraine and Britain to collaborate in the Azov Sea.
Zakharova described the agreement as a publicity stunt by the Ukrainian government, aimed at creating an illusion of strong alliances.
The agreement was signed during a visit by British Prime Minister Sir Keir Starmer to Ukraine on Thursday. The published document outlines plans for the establishment of military bases in Ukraine and cooperation on long-range weapon systems.
MNA