"It is our right to defend ourselves, without interfering in the affairs of others. We call on others to not interfere in our affairs," Salman said in a speech opening the annual Janadriya cultural festival in Riyadh, state news agency SPA reported.
"We cooperate with our Arab and Muslim brothers in all areas in defending our lands and ensuring their independence and guarding their government systems as sanctioned by their peoples," he added.
Salman did not elaborate, but his remarks seemed aimed at Iran, which Riyadh accuses of destabilising Arab states and spreading sectarianism by backing militias in Syria, Lebanon, Iraq and Yemen and fomenting unrest in Bahrain and Saudi Arabia.
Iran denies seeking to destabilise the region or incite sectarian hatred. It in turn accuses Riyadh of fomenting discord by backing rebels in Syria, going to war in Yemen and propagating an ultra-conservative Sunni Muslim school that declares Shias heretical.