Americans should not breath a sigh of relief just because a computer hacking group said it would suspend a four-month offensive to disrupt access to more than two dozen bank websites. Even if the al-Qassam Cyber Fighters group says it won’t attack PNC Bank and other financial institutions, cyber attacks meant to disrupt commerce in the United States are likely to continue, said Jeff Bardin, a Boston cyber security consultant and expert in Middle Eastern hackers and cyber jihad.