Yes they were.

As far as I know, the first meaningful contact between the Greco-Roman world was when Alexander the Great showed up in India. Successors of Alexander, particularly the Seleucids, maintained relations with India until their Eastern provinces were lost.

After that, trade between India and the Roman was facilitated by Ptolemaic Egypt, via the Red Sea. The Romans, after they took over Egypt, continued to facilitate this trade. Augustus himself received diplomatic embassies from Indian countries.

I know it's Wikipedia but the article is a decent starting point on Indo-Roman relations, https://en.wikipedia.org/wiki/Indo-Roman_relations plenty of quotes from Pliny and other authors.

In broad terms, I hope that suffices to answer your question - yes, the Romans and Indians were both aware of one another and appear to have had a reasonable amount of contact.

Since it's probably of interest to you as well, I'll just mention that the Romans and the Chinese were apparently aware of each other, albeit in very vague terms. Certainly they managed to have indirect contact through trade (Roman silk came from China, after all), and apparently there were sporadic attempts at sending embassies which didn't seem to meet much success. Again, perhaps of interest as a starting point for further research: https://en.wikipedia.org/wiki/Sino-Roman_relations