The Home Office said 15 men were taken by Border Force staff to Dover, where 11 of them, all identifying as Iranian, were passed to immigration officials.
The other four were arrested on suspicion of facilitating illegal entry into the UK.
Their arrival follows the discovery on Sunday of a family of seven in Kingsdown, on the Kent coast.
In the latest operations, Border Force vessels collected the groups – nine on one small boat and six, a few hours later, on another – and took them to Dover harbour.
It takes the number of migrants attempting to reach the UK via the English Channel in 2019 to more than 100.
The total number arriving since last November is now more than 350.
The men arriving in Dover, who the Home Office said were all “medically well”, were initially met by Border Force staff following guidance that coastguard rescue volunteers should no longer provide routine humanitarian support to migrants arriving via the English Channel.
Until now, coastguard rescue staff have helped with blankets, tents and medical assistance when new migrants arrive.
But now the volunteers will intervene only in emergencies.
The policy change has been criticised by migrant support worker Ben Bano, who said: “I see this as hostile environment creeping in more and more.”
But the Home Office said all Border Force maritime officers underwent sea-survival courses, which included first-aid skills, before deployment.