Somali nationals are among those banned from travelling to the US under the executive order issued on Friday.
That had applied to Farah, who was born in Somalia, until the announcement by the UK Foreign Office late on Sunday.
Farah, 33, called Trump's policy "divisive and discriminatory".
Trump's executive order halted the entire US refugee programme and also instituted a 90-day travel ban for nationals from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen.
