The news agency did not name the church in the southern city of Madurai where the missionaries worked, but said the order for them to leave India was issued by the Home Ministry in New Delhi.
They were told to pack their bags as they did not renew their visa papers in time, PTI quoted a ministry source as saying in New Delhi.
Officials at the U.S. embassy here were not immediately available to comment on the development, the first involving American priests working in India in recent years. Madurai administrator Mani Bharathi, however, said the marching orders came when the missionaries did not present themselves before the local police for the renewal of their travel papers in line with an Indian rule for foreigners.
The missionaries told PTI that they were "disappointed" by the directive and that they would leave for Sri Lanka and return in case the issue was settled with the Indian government.
Both foreign missionaries and Indian Christians have complained in recent years of increased hostility -- and violence -- from the nation's Hindu majority as Hindu militants have gained increased political power.
Hindus complain that Christians try and convert poverty-stricken, lower-caste Hindus with offers of material gain. Hindus say such attempts upset age-old social and cultural norms and cause strife between the religious groups.
India has also experienced an upswing in Hindu-Muslim violence during the same period.