अत्र here in this case, मन्युः indignation, नकर्तव्यः as my duty, त्वाम् to you, रोषये not to cause anger, नभीषये not to cause fear, वीर्येण in valour, सुराणाम् Devatas, निग्रहेऽपिमोल can resist, समर्थः capable, असिहि am telling.

"Here, in this case do not be angry. I am telling out of my duty and not out of indignation or to cause anger or fear in you. You are capable of resisting even Devatas."