This website mention that Lord Rama's ancestor Mahārāja Raghu used Narayanastra on Ravana.
Was there an encounter between them? Where is the story can be found?
Hinduism Stack Exchange is a question and answer site for followers of the Hindu religion and those interested in learning more about Hinduism. It only takes a minute to sign up.Sign up to join this community
According to Valmiki Ramayana, battle did not take place between Raghu of Ikshvaku dynasty and Ravana.
However, battle did take place between Anaranya of Ikshvaku dynasty and Ravana. This was mentioned by Ravana himself after the 1st encounter with Sri Rama in which he was defeated and was spared by Sri Rama.
विदितम् मानुषम् मन्ये रामं दशरथात्मजम् | इक्ष्वाकुकुलजातेन अनर्ण्येन यत् पुरा || ६-६०-८ उत्पत्स्यति हि मद्वंशे पुरुषो राक्षसाधम | यस्त्वाम् सपुत्रम् सामात्यम् सबलम् साश्वसारथिम् || ६-६०-९ निहनिष्यति सम्ग्रामे त्वाम् कुलाधम दुर्मते |
"Rama the son of Dasaratha is the man I think of whom Anaranya born of Ikshvaku dynasty formerly spoke, saying: 'O, the worst of demons, the worst of your race and the wretched one! In my race will be born a man who will slay you in battle with your sons, ministers, army, horses and charioteer."