The forces in West and North Yorkshire have both said they are increasing patrols as Muslims head to their Friday prayers.
Home Secretary Sajid Javid will also hold talks with anti-terrorism chiefs and security officials to discuss possible further measures to protect mosques in the UK.
Forty-nine people have been killed and at least 20 wounded in shootings at two mosques in Christchurch, New Zealand. Four people have been arrested.
Temporary Assistant Chief Constable of North Yorkshire Police, Ciaron Irvine, said: “Although it may be on the opposite side of the world, the impact of this terrible act of terrorism will be felt by people everywhere.
“As a police force our hearts go out to those who have been affected, their families and friends, and those in emergency services who are dealing with this aftermath of this cowardly attack.
“Here in North Yorkshire we have already been in touch with the mosques in our area to confirm that we will maintain a special focus on mosques and step up patrols in the vicinity as a reassurance measure.”
West Yorkshire Police Temporary Chief Constable John Robins said: “We stand together with our Muslim communities and all those shocked and horrified by this terrorist attack in New Zealand.
“Today’s tragic events demonstrate that attacks can occur at any time and without warning. There is no new increased threat to West Yorkshire. The UK threat level remains at Severe meaning an attack is highly likely.
“Today we are stepping up reassurance patrols around places of worship and increasing engagement with communities of all faiths.”
South Yorkshire’s PCC, Dr Alan Billings, has also condemned the attack.
The forces also urged members of the public to remain vigilant and to call the Anti-Terrorist Hotline on 0800 789321 if they see anything suspicious or 999 in an emergency.
National policing lead for counter-terrorism Assistant Commissioner Neil Basu said: "Together with our intelligence partners we continually monitor the varied threats we face, including to and around places of worship and specific communities across the country, to ensure we have the most appropriate protective security measures in place to keep people safe.
"Today we will be stepping up reassurance patrols around mosques and increasing engagement with communities of all faith, giving advice on how people and places can protect themselves."
Security minister Ben Wallace told the House of Commons that he and the Home Secretary would be speaking with police counter-terrorism leaders and security services "to discuss what further measures we can take to protect our mosques and our communities from any threats here in the United Kingdom".
Harun Khan, secretary general of the Muslim Council of Britain (MCB), called on the Government to redouble efforts to ensure mosques are protected.
He said: "As the rest of us prepare to undertake our own Friday prayers today, we do so with the anxiety as to whether our mosques and communities are safe in the face of unabated Islamophobia and hostility against Muslim."
The MCB also urged the Home Office to keep open its places of worship security fund on an ongoing basis.
Launched in 2016, the scheme helps churches, mosques, temples and gurdwaras to install alarms, security lighting and CCTV cameras to deter attackers.
Bids for up to £56,000 per place of worship could be submitted between June and August last year.
The potential for mosques to be targeted was underlined in the Finsbury Park attack in 2017.
Experimental figures published by the Home Office last year indicated that in 2017/18, where the perceived religion of the victim was recorded, just over half (52%) of religious hate crime offences recorded by police in England and Wales were targeted against Muslims.
British security chiefs have warned of a rising threat from far-right terrorism.
Police say they have foiled four extreme right-wing plots in the last two years.
MI5 is taking on an increased role in assessing and investigating extreme right-wing terrorism, which police have historically led on.