WASHINGTON — Nigeria’s top diplomat said on Tuesday that he was “somewhat blindsided” by the Trump administration’s ban on Nigerian immigrants but that he had been assured by American officials that visa restrictions could soon be lifted.

Geoffrey Onyeama, Nigeria’s foreign minister, said that his government was already working to address security concerns that Trump administration officials said had prompted the decision, announced last week, to reject visas for Nigerians seeking to immigrate to the United States.

“We were somewhat blindsided with the announcement of the visa restrictions by the U.S.,” Mr. Onyeama told journalists at the State Department. But, he said, “we know — and the U.S. officials have also confirmed — that we have been able to tick most of those boxes.”

He said that included efforts to directly share personal data — including immigrants’ criminal histories, stolen passport information and suspected links to terrorism — with the United States and Interpol member countries.