Foreign Minister David Owen told the House of Commons yesterday that Rhodesia's so-called internal settlement was good but not good enough.

It was his first formal response to the deal strack last week by Preme Minister Ian Smith and black Rhodesian nationalists living inside the country.

Owen told the House," "I am not prepared to condemn or support what at this stage is an important first step along a path on which there is much further to go."

For some time, Britain has shown indications of moving away from a sparate Anglo-American effort to negotiate asettlement which would also involve the Patriotic Front guerrillas, who are based outside Rhodesia and have been excluded from last week's agreement.

The African territory, still legally part of Britain, is one of the few areas left in the world where London's view is crucial. Without approval here - and in Washington - there is no chance that the U.N. trade sanctions crippling Rhodesia's economy will be lifted.

Washington is said to understand that domestic politics inhibit Owen's open dealings with the Patriotic Front. The opposition Conservative Party, some of whose members have large mining interests in Rhodesia, are strong supporters of Smith. They have been pressing the Labor Party government to accept the internal deal Smith has arranged and denounced the government for trucking to "Marxist terrorists.

To protect his right flank, Owen must therefore tread with caution in dealing with the Patriotic Front.

The British stance has a quality of looking two ways at once. Owen's aides insist, however, that a measure of consistency underlines the position and it is still in lockstep with Washington. American diplomats here do not quarrel with this view.

The argument goes that the internal deal seemingly provides for black majority rule which is all to the good. It is condemned, however by the leaders of the black forces conducting the guerrilla war against theSmith gov-Nkomo and Mugabe Have indicated in ernment, Joshua Nkomo and Robert Mugabe.

As long as they hold out, it will be difficult to test the sentiment of Rhodesia's blacks, will threaten Anglo-American ties with neighboring black states and will serve as an open invitation to Soviet Cuban intervention.

Owen held talks yesterday with Bishop Abel Muzorewa, reputedly the most popular black leader to accept the internal deal. Owen is understood to have stressed that the pacta was simply a first step, thata there was a long way to go and to haave sketched out how to arrive at a "genuine" agreement.

The foreign minister is understood to have said that the deal can not be regarded as genuine until the leaders of the Patriotic Front, Nkomo and Mugabe, sign on. Their hostility could be justified because the arrangement with Smith leaves control of Rhodesian soldiers and police in white hands at least until after an election. In addition, it appears to provide for a white veto over any important legislation for another 10 years or more.

Apart from these considerations, the past that they simply want power turned over to them and their guerrillas before any constitutional arrangements are worked out.

Muzorewa emerged from one three hour session with Owen to say he was "extremely encouraged" because Owen had not rejected the internal pact out of hand.

Owen went even further in a little-noticed radio talk show over the weekend. There he said the internal pact met all the major Anglo-American objectives except for the failure to get a cease-fire and the agareement of the Patriotic Front.

It may be, he said, that "you might have to choose between the lesser of two evils... You can't give a veto to any one party, nobody, whether they they are people who have guns outsidethe country or people who have guns inside the country..."

If Rhodesia's blacks declare, in a "fair and free election," that this is what they want, "If it's acceptable to them, then I believe the British Parliament would have to face the difficult issue of choosing."

Now, Anglo-American tacticians are concentrating on "engging" Nkomo and Mugabe in negotiations to narrow their differences. Owen has proposed that they, along with Muzorewa, put their cases to the U.N. Security Council in New York.

Muzorewa's aides say that the bishop, who flies to Washington today to try to sell the deal to the Carter administration, is not averse to appearing before the Security Council. Third Wourld members might well refuse to hear him, insisting that Nkomo and Mugabe are the only legitimaate representatives of black Rhodesians.

There have been press reports from Lusaka, Zambia, that the United States and Britain are split, with London warmer to the internal pacta and Washington closer with the Patriotic Front.

Those in a position to know here deny that there is any riff over any major feature of the Rhodesian tangle. On tactics, the United States is more prepared to make contact with Nkomo and Mugabe than Owen. Although he they and U.N. Ambassador Andrew Young were all together recently in Malta.