A firework was aimed at members of a strictly Orthodox North Manchester synagogue last weekend, and antisemitic graffiti scrawled on its window.
A rocket was lobbed from a passing car as members of Beis Mordechai Synagogue in Prestwich gathered outside after evening prayers on Sunday, and the words "scruffy Jewish Basterd [sic]" were scrawled across a window.
Police are treating the graffiti as racially aggravated criminal damage, but the firework attack was not thought specifically to target Jewish people.
A Greater Manchester Police spokesman said: "As a result of the incidents, and in preparation for the Jewish holidays, GMP is providing extra patrols in the area to reassure residents."