Sudhanshu Trivedi, national spokesperson for Modi's Bharatiya Janata Party that won a resounding victory in recent elections, said there had also been "many apprehensions" about the Hindu nationalist BJP before it last took power in 1998.
But the 1998-2004 BJP government of prime minister Atal Behari Vajpayee "was the golden era of Indo-US relations, so we have proved that we are capable of maintaining relations to new height," Trivedi told a conference in Washington by phone.
Modi was refused a US visa in 2005 on human rights grounds due to riots three years earlier in his state of Gujarat.
Trivedi, addressing a largely sympathetic audience at the US India Political Action Committee, an Indian American group, did not bring up the visa issue.
But he criticized outside perceptions of Modi, saying the BJP "should not be seen as right-wing fundamentalist.