The party, which is a part of the Congress-led UPA at the Centre, made the demand saying this was needed according to principle of propriety as the issue is serious.
Replying to questions, party spokesman D P Tripathi told reporters that he was not demanding that Tharoor step down as a minister.
He also dismissed suggestions that his demand was due to compulsions of the politics of Kerala where the NCP is part of the Opposition Left Democratic Front.
"We really mourn Sunanda Pushkar's death from the core of our heart. However, the matter is serious and investigations are on and Tharoor has rightly pledged that he will cooperate with investigating agencies. We think Tharoor will himself disassociate from his ministerial responsibility till the investigation is over," Tripathi said.
Reports earlier had it that BJP's Kerala unit demanded the resignation of Tharoor from the Union Ministry in the backdrop of the death of his wife. Tharoor is a Congress member of the Lok Sabha from Thiruvananthapuram.