HONOLULU — President Barack Obama signed a wide-ranging defense bill into law Saturday despite having "serious reservations" about provisions that regulate the detention, interrogation and prosecution of suspected terrorists.

The bill also applies penalties against Iran's central bank in an effort to hamper Tehran's ability to fund its nuclear enrichment program. The Obama administration is looking to soften the impact of those penalties because of concerns that they could lead to a spike in global oil prices or cause economic hardship on U.S. allies that import petroleum from Iran.

In a statement accompanying his signature, the president chastised some lawmakers for what he contended was their attempts to use the bill to restrict the ability of counterterrorism officials to protect the country.

Administration officials said Obama was only signing the measure because Congress made minimally acceptable changes that no longer challenged the president's terrorism-fighting ability.

"Moving forward, my administration will interpret and implement the provisions described below in a manner that best preserves the flexibility on which our safety depends and upholds the values on which this country was founded," Obama said in the signing statement.

Signing statements allow presidents to raise constitutional objections to circumvent Congress' intent. During his campaign for the White House, Obama criticized President George W. Bush's use of signing statements and promised to make his application of the tool more transparent.

Obama's signature caps months of wrangling over how to handle captured terrorist suspects without violating Americans' constitutional rights.

The White House initially threatened to veto the legislation but dropped the warning after Congress made last-minute changes.

Among the changes the administration secured was striking a provision that would have eliminated executive branch authority to use civilian courts for trying terrorism cases against foreign nationals.

The new law now requires military custody for any suspect who is a member of al-Qaida or "associated forces" and involved in planning or attempting to carry out an attack on the United States or its coalition partners.

The president or a designated subordinate may waive the military custody requirement by certifying to Congress that such a move is in the interest of national security.

Obama signed the bill in Hawaii, where he is vacationing with his family.