Two city centre Barclays branches have been covered in red paint and graffiti and had glass doors smashed as part of a protest in support of Palestine.
Protest group Palestine Action (PA) said its activists were responsible for the attack on the bank’s sites on Market Street and Mosley Street in Manchester.
A nearby Bank of New York Mellon site also had graffiti daubed on it.
A Barclays representative said it had reported the attack to Greater Manchester Police and added that while respected the right to protest, campaigners needed to “respect” its buildings and not put “people at risk”.
They added that the safety of customers, colleagues and the local community was “our priority”.
In a statement, PA said it had targeted the banks over alleged investments in Israel-based military technology firm Elbit Systems.
The Barclays representative said it did not directly invest in any weapons firms, but did provide “vital financial services” to US, UK and European public firms that supply defence products to NATO and its allies”.
Greater Manchester Police confirmed officers were investigating the damage.