"If I get married and have children, I will be status-quoist and will like my children to take my place," Mr Gandhi, 42, told party members in New Delhi on Tuesday.
"Does that mean those of us who are married are not capable of serving the nation?" asked BJP spokesperson Shahnawaaz Hussain.
Mr Gandhi was recently named to the number two post in the ruling Congress party, which is headed by his mother, Sonia Gandhi.
His famous surname and youthful image make him the party's main hope for next year's national elections, but has said his main mission is to democratise the Congress party and promote youth leaders.
Mr Gandhi yesterday dodged questions about his own aspirations, saying he was not focused on becoming prime minister in remarks likely to worry party leaders who are betting on his star power a year ahead of polls.
"Asking me whether I want to be prime minister is a wrong question," he told party members in New Delhi.
Some analysts interpreted the comment as signalling that he would seek to follow his mother's example by nominating a prime ministerial candidate while wielding power behind the scenes, if the Congress wins a third term next year.
Sonia Gandhi named Manmohan Singh as prime minister after elections in 2004.