The lira was trading at 5.9 to the US dollar, a loss on the day of more than 6 percent. The lira has weakened nearly 37 percent since the beginning of the year, though it had recovered some losses.
Turkish President Recep Tayyip Erdogan urged Turks to exchange foreign currency to support lira.
Washington believes that he was jailed unlawfully. Ankara has scolded the US sanctions and promised to freeze US Justice and Interior Secretaries' assets in Turkey.
Brunson was detained in 2016 on suspicion of links to the movement founded by Islamic cleric Fethullah Gulen, who Ankara holds responsible for the failed coup attempt that same year.
The pastor was recently released from a Turkish prison last week and placed under house arrest.