Ivanka Trump on Monday expressed solidarity with worshippers attacked while leaving a London mosque, while her father -- usually quick to condemn extremist attacks -- was silent for the time being.
"Sending love and prayers to the victims in #FinsburyPark London. We must stand united against hatred and extremism in all it's ugly forms," Ivanka, a top presidential advisor, tweeted.
President Trump has taken to Twitter during previous terror attacks to make the case for tighter restrictions on travel from predominantly Muslim countries.
He has also yet to offer public comments on the deaths of seven US sailors, who were killed during a collision between their US navy destroyer and a Philippine-flagged cargo ship.
In the London attack, a van ploughed into a crowd of Muslims near a mosque early on Monday, leaving one person dead and injuring 10 others in the second terror attack this month in the British capital.
Prime Minister Theresa May condemned the "sickening" incident, saying Britain's determination to fight "terrorism, extremism and hatred... must be the same, whoever is responsible".