European Union leaders are boycotting the ceremony in May over Russia's role in the Ukraine conflict but Zeman -- who has frequently departed from the EU line -- has said he would attend.
"I can’t imagine the Czech ambassador in Washington would give advice to the American president where to travel," Zeman told news portal Parlamentni Listy. "I won’t let any ambassador have a say about my foreign travels."
"Ambassador (Andrew) Schapiro has the door to the castle closed."
A presidential spokesman told local media that Schapiro could still attend social events at Prague Castle, the official residence of the Czech president.
Schapiro told Czech television earlier this week it would be "awkward" should Zeman attend the ceremony as the only statesmen from an EU country.
Zeman, a former prime minister, has frequently departed from the common EU line on Ukraine and criticized sanctions against Moscow. The government, which is responsible for foreign policy, however, has held the EU line fully.
The Czech presidency is largely a ceremonial role but Zeman - who was the first president directly elected when he took office in 2013 - is outspoken on his views on both domestic and foreign policy.