The Polish Gazetà Wyborczà newspaper earlier reported that the U.S. and Poland could sign a missile base agreement this spring.
"The decision [on the U.S. missile base] has not been made yet," Radoslaw Sikorski said.
The U.S. plans to deploy 10 interceptor missiles in Poland and a radar in the Czech Republic citing a threat from Iran and other "rogue states," while Russia views these plans as a destabilizing factor for Europe and a threat to its national security.
The minister reiterated that Poland is seeking to strengthen its missile defenses and thereby expand its capabilities as a U.S. ally in Europe.
The Bush administration earlier said it backed Warsaw's request for aid in modernizing its missile defenses.
Poland's new government led by Donald Tusk, which came to power in November last year, has taken a more cautious approach to the U.S. proposal than former Prime Minister Jaroslaw Kaczynski's cabinet, which fully supported the plan.