The National Transport Authority (NTA) has encouraged people to only use public transport for essential journeys while the two-metre social distancing guideline remains in place.
CEO Anne Graham said that, as demand grows, people are occasionally being left behind at bus stops.
Speaking on RTÉ's Today with Sarah McInerney, Ms Graham said that additional bus capacity is available to assist with an increasing demand in the use of public transport at peak times.
She added that as Ireland enters Phase 3 of the easing of restrictions, "it will become increasingly difficult to maintain two metres social distance at peak times.
"This is why we are encouraging people, while the two-metre social distancing is in place, that people only use public transport for essential journeys and that they stagger the times of travel."
Social distancing at bus stops will also become more difficult as demand increases, Ms Graham said, and the NTA is funding local authorities to help create additional space at bus stops.
"We are encouraging people to travel at off-peak time particularly if it is for non-essential travel.
"We are also encouraging employers to allow people to keep working from home, and as much as possible to consider walking or cycling to work to take pressure off the system and keep it available for those who have to make essential journeys."
She said it is a matter for government as to whether the two-metre distancing rule is reduced.
Wearing a face covering on public transport remains an advisory measure, Ms Graham said, but the NTA is encouraging as many customers as possible to do so.
She added that the responsibility lies with the public transport user to wear a face covering.
